T100T

Hi to everyone,

Car is a 2010 E550, 155k miles, earlier this week when I headed out to the office the vehicle died, less than 1/4 mile from home. Since then it starts easily but runs for no more than 2 seconds before dying. It felt like a fuel supply issue but connecting a gauge showed normal pressure.

I connected to the OBII port, and the scan (Xentry) showed four faults under the header N3/10 - Motor electronics 'ME97' for combustion engine 'M273' (ME), details below...

Fault - Text
0868 - The control unit has a malfunction
1108 - The power supply at the input of the control unit 'combustion engine' has a malfunction
0224 - Adaptation of the idle position of the throttle valve actuator was no performed
0120 - Position sensor 1 for the crankshaft has a malfunction

Under the details of all four of the above faults there is a battery voltage and each shows less than 2 volts.

I have WIS but the circuit diagrams they're not for the novice, for instance what is N3/10? It's listed under the Xentry scan but also in the circuit diagram where it looks like a connector. Seems either I've a wiring issue or the control unit has failed - I guess digging into fault 1108 is the easiest place to start - does anyone know where to check the voltage the control unit is receiving?

Appreciate any help,

Peter

CaliBenzDriver

You got a good one mate, live faults are all over the place within the ECU boundaries.

Let's cover the basics before diagram time.

Fuel pressure is good... single pump, no GDI, right?

The ECU reports over OBD2, so indeed it is still running, not toasted 👍

ECU does complain about some low-voltage 02VDC business.... so check your F-SAM Fuses: one of the many ECU actuator circuits may be missing power feed.

What do you feel like taking apart??

Do we have a collection of sensors missing +12/GND ?

While checking fuses... can you spot signs of oxidation??
✌️

++++++++ LUCKY FAULTS ???

These 2 faults spell kill the engine ASAP :

0224 - Adaptation of the idle position of the throttle valve actuator was no performed

0120 - Position sensor 1 for the crankshaft has a malfunction !!!!!!!!!!!!!!!!! your ticket!

ECU is doing coherent work :
CKP SENSOR ISSUE
UNTRAINED THROTTLE BODY

Fat chances it's a minor issue, you won't have to hand over your wallet for this.

Xentry playtime:
Go look at CKP first, its the maestro sensor that drives everything else.

Good for you

T100T

Cali, thank you for replying,

I just checked all the fuses in the box on the driver's side of the engine compartment next to the firewall, one was bad #25 - will go to the store and buy some replacements. The F SAM fuse looks tricky to get into, so I'm going to see if replacing the #25 fixes things.

There was no corrosion in the fuse box. However, I am seeing some other electrical gremlins which may be related but first let's see if we can get the car running again.

Will report back tomorrow.

Thanks again,

Peter

juanmor40

https://fuse-box.info/mercedes-benz/...uses-and-relay

#25 -> ME-SFI CONTROL UNIT

CaliBenzDriver

yeah, follow Fuse#25 to see what it has in common with your faults.
Fuses are seldom the cause. Promise yourself you will resist upgrading fuse with a paperclip.

So far your ECU is likely ok besides blown fuse#25 pointing towards it. I think it's one of the circuits cooking like harness of O2/Lambda.

Now you'll need a schematic to trace fuse#25 around the ECU peripherals.

S-Prihadi

Sometimes it amazed me on how MB diagram maker is trying to make life difficult for techy or DIY owners.

Often, wiring diagram for N3/10 engine computers, on purpose is made to be tricky ..... by not showing ALL THE FUSES there then...... what the hell they been smokin'


Wow, so many fuses for M273 engine computer.

Attached M273 engine computer wiring diag


This is Front SAM for W212 easy and fast fuse & relay finder I made some years ago, to reduce migrain. Have a go......

CaliBenzDriver

Thanks to @S-Prihadi for sourcing a matching diagram, we see the Fuse#25 feed rushed straight into the ECU.

F25 is ECU + Z7/73 splice !!!

If your car has a big appetite for F25, this won't be easy to trace!


circuit 87...

From there we may be forced to go on limbs...
F25 is feeds splice Z7/73 called "circuit 87" and these circuits 87 branches are all around the ECU diagram...


> What can you do...
If F25 is short lived, short of replacing ECU to find out the exact same thing keeps up...

-- Now is the time to unplug all sensors and circuits ECU directly complains about with a fault#.

-- If that's not enough make a bigger circle with parts that may not be running. (Obviously coils, injectors... are working regardless of bad F25, so these remain unsuspected).

Obviously engine is not going to run without CKP but all we want is a chance to find out what else can blow F25 besides the ECU itself.

🤞

T100T

Thank you for the replies, fuses arrived, installed new 15A fuse in slot 25, re ran Xentry diagnostics same error msgs, fuse blown. On reflection I think this is good news as I'd rather have a hard fault than an intermittent one.

Looked through S-Prihadi's reply and went on WIS, here's where my fumbling got me...

- WIS for my VIN group 15, Electrical system - engine, 15.18 Cable sets. Information type "Circuit diagrams". Search has a link to "Search aid for all electrical components", that takes you to a very long list of documents, only those for my VIN were highlighted, I saved that to a PDF so I could search it.

- Searched the PDF for "f25" as that seems to be the identifier for a fuse, there was a single hit for that with the full identifier N10/1f25, back to the WIS list and scroll down to that and hit the link. This takes me to something called "Sheet 6" which jives with what S-Prihadi mentioned.

- I don't know what the U numbers signify, so began clicking links. X26 took me to another list with two links for my engine, looking at the "location" link gave me this, I disconnected the two connectors X26/1 and X26/2.

- Downstream of X26 was Z7/98z3, that is what is called a "M3e connector sleeve" which seems to be a joint buried in the harness - it looks as though it branches to the ignition coils for the two sides of the engine. Having disconnected X26 it should be out of the circuit.

- Next was the link for PE 54.15-P-2109DAA under U968, which has K40/10 written on it, this drawing also contains the f25 fuse which powers 87M which appears to be the main "Motor electronics" supply. These control two, what look to be relays, kU and KS, looking at juanmor40's link they are in the "Engine compartment additional fuse box (hybrid)", physically I don't see that fuse box on my car, does it exist? If it does I need to find it, from juanmor40's link it looks to have quite a lot going on.

- Moving along under U880, tracing from there the 87M line is goes to a point Z7/48 and on two CAN connectors N37/7 and N37/8, these are Nitrogen oxide control units, the /7 refers to diesel, /8 to catalytic converter. Z7/48 is another connection in the harness, looks to be buried by the front passenger door sill. Does anyone know where the N37/8 is located?

- U127 took me to a wiring diagram which did not include f25, nor U127.

- U1032 was the same as U127, no references to f25.

- Code U42, as far as f25 was concerned, was a repeat of what was on U880.

I'm going to do some more searching for devices connected to 87M before trying another fuse.



Since starting to write this there have been other replies.



Peter

CaliBenzDriver

Peter the Great, your up for it


I would follow that z7/73 splice ....

make a flat-tree with members, we'll help you pick suspects.

Yes exactly :
"I'm going to do some more searching for devices connected to 87M before trying another fuse".

pasted from previous:

> What can you do...
If F25 is short lived, short of replacing ECU to find out the exact same thing keeps up...

-- Now is the time to unplug all sensors and circuits ECU directly complains about with a fault#.

-- If that's not enough make a bigger circle with parts that may not be running. (Obviously coils, injectors... are working regardless of bad F25, so these remain unsuspected).

Obviously engine is not going to run without CKP but all we want is a chance to find out what else can blow F25 besides the ECU itself.

T100T

CaliBenzDriver/S-Prihadi, thanks for replying, which document are you pasting from? In my document list PE54.21-P-2106DAF is N10/1f25 which corresponds to Sheet 6 of the N10/1 document, PE54.21-P-2106-97DAF is the actual wiring diagram, see attached.

Peter

T100T

I looked at the harness and the wires look to be in good shape, the majority of the wires are in protective sleeves/plastic moldings but what can be seen doesn't appear cracked or damaged. Pigtails have been fitted at the crankshaft position sensors and there was no oil in those. The tiewraps that keep the plastic conduits together are tending to fall apart when touched but that's probably to be expected. There is a small electric fan connected to the front of the engine, the output goes into the airbox - I disconnected it as it's one of the few items with large gauge wires, beyond that the rest of the engine harness (except the ignition connections X26) looked to be sensors.

So now is maybe a good time to add another possibly related piece of information, don't flame me for not adding this earlier. About 15mths ago I started to get the message to check oil level at next fill up, I did and the oil level was fine, when next doing an oil change I replaced the sensor. Well less than 12 mths after that I started getting the same message (not every day but probably once every two weeks) and again the oil level was good. So again at the oil change I changed the sensor but this time I checked both the old and new sensors. It's a very simple device, takes a single wire and if I recall it goes open circuit when oil level is low. My thinking is that in fact there is an issue with the wire harness, perhaps it is shorting some other power line (one that can deliver over 15A current) in the harness. That might explain my intermittent low oil level warning messages and represent a short to some other circuit. I'm going to try and trace the oil level sensor wiring.

Appreciate the feedback,

Peter

CaliBenzDriver

I used the diagram researched by master Surya in Post#6 - Your diagram does look a bit different.



F25 bus



The focus is to trace everything feeding from F25 and hope we can disconnect a bad guy.

​​​​​​
> Ohming the short :
In the mean time, can you measure the resistance on the load side of the open fuse....
-- is it a 0.1 Ohm dead short
-- is it a heavy load less than 0.86 Ohms
Then unplug the ECU, measure load again.

This test is going to give you some idea about your ECU electrical fitness.


++++++ testing the short status : DVM > Live
While the ECU is disconnected (or whatever we believe is acting like the short):
-- measure the load resistance greater than 0.90 Ohms or plug a new F25 fuse to confirm the short is gone.

At least that was a fuse well spent

T100T

CaliBenzDriver,

There are two connectors to the ECU, the one on the drivers's side is marked F, passenger is M. With both connected insulation from the f25 fuse receptacle (side closest to engine) is between 0.7 and 1 ohm, this goes to open circuit when the F connector is unplugged, removing just the M connector has little effect. That value seems low given the fuse is only 15 A, so it looks like a hard failure downstream of the ECU or the ECU itself but probably unrelated to the devices that have been disconnected. I'm assuming less than 1 ohm is bad, i.e. I'm seeing my hard failure.

I disconnected both F and M and installed a new f25 turning the ignition on gives a different set of error messages on the dash, all sorts of stuff not working, the fuse does not blow. I did in fact momentarily (less than 5 seconds) connect the f25 without disconnecting the ECU but did not turn on the ignition and the fuse did not blow.

It seems I've a number of options as this point...

(i) wiggle wires around with an ohmmeter connected to the f25 socket, see if it changes.
(ii) disconnect anything I can on the engine harness, again with the ohmmeter attached, there are a few sensors but not a whole lot, I do that by tracing the harness wires, see if ohmmeter readings change.
(iii) see if I can get a wiring diagram that shows the connections in the ECU F connector and ohm out those pins, would do this will devices all attached. Any tips on how to find into on a connector in WIS documentation?

Always open to suggestions...

thanks again to all who've added to this posting,

Peter

T100T

OK, so I'm coming full circle to what S-Pirhadi wrote, N3/10 is the ECU and the engine connector is marked M while the vehicle is marked F. So I'm focused on the F connector, there are lots of fuses shown on this but no f25. The vehicle PDF contains a list of devices you'd expect the ECU to be involved with like the fuel pump, drive train stuff, accelerator pedal, etc; so I'll work my way through those. There are also lots of wires whose labels begin with 87M, I can ohm those to ground.

That's enough of a plan for now,

Peter

S-Prihadi

Navigating MB wiring diagram for Front SAM N10/1 , is not easy unless you got used to it and do the process of elimination first.
What is the process of elimination ?
Front SAM wiring diag is for 50+ variants of MB cars, as such they packed so much information, one will waste hours getting lost due to clicking the wrong wiring link, because one does not first
do the process of elimination.

If you use a small screen device trying to read Front SAM wiring diag, unless your eyes is still 20/20 ( 20/20 : me when was at 35 years old ), you will make a lot of mistake.
Twin 27" screen PC is what I use, as flipping between legends and the wiring trace, is no fun on a small and single screen,

DO NOT ALWAYS TRUST THESE : in red
Peter Wrote :
"Search has a link to "Search aid for all electrical components", that takes you to a very long list of documents, only those for my VIN were highlighted, I saved that to a PDF so I could search it.
If your car version is a Pariah like mine E400 and M276 3.0 Turbo , you will suffer even more as those automatic link often goes to wrong document.


Peter wrote :
I don't know what the U numbers signify, so began clicking links.
That is where the Legend in each and every wiring diag 1st few pages if in PDF or right side window in WIS MB ....will show you what those meant and often you must first print out your car DATA CARD
using a VIN Decoder because those codes are often shown on our data card.
Example B03 is Start-Stop. Code 580 is regular air conditioner and Code 581 is the more advance air conditioner system.






So what is the process of elimination ?
Cross out or remove all link which is not FOR OUR CAR.



See the engine computer wiring diag I posted first time yesterday to show you the where fuse 25 is from.........


See, how useful a big screen is for ease of work.

==================

This is my own Front SAM sheet 6 wiring which I have audited and stitched all pages to become 1 page and make it to JPEG. Because I do not want to get headache when looking at Front SAM wiring for WHAT IS NOT FOR MY CAR .



Zoomed to fuse 25




Now, do the process of elimination first as to not confuse yourself.
I will help you later...OK

S-Prihadi

That is why I label where F25 is actually connected to N3/10 engine computer in my very first post. See red F25
I also mentioned :
"Sometimes it amazed me on how MB diagram maker is trying to make life difficult for techy or DIY owners.

Often, wiring diagram for N3/10 engine computers, on purpose is made to be tricky ..... by not showing ALL THE FUSES there then...... what the hell they been smokin' "





N10/1 is the ID of FRONT SAM fuse box, inside there are computers board too, not only fuses and relays
N10/2 is the ID for REAR SAM fuse box at the trunk, inside there are computers board too, not only fuses and relays

N3/10 is the ID for gasoline engine computers.
N3/9 is the ID for diesel engine computers


Your fuse 25 from Front SAM ( sheet 6 ) is only and only for the engine computer, F connector pin 3 and 5, that is it, it does not go or be connected to anything else.
See the word F at the very left top of the drawing, that means F connector, the short one the 56 pins. The M connector is the long one, like 96 pins.




Now you need to be careful here as blowing a 15 amps fuse, if repeatable blowing up, is not a good sign because the consumer of that fuse is an expensive ECM.
This fuse is probably what supplies the 5V sensors and injectors and ECM internal processor. We don't really know all these as there is no in depth wiring diag for ECM internal.

There are other fuses for ECM related duty, but some do not get connected to the ECM directly, but rather to the sensors/devices directly and the ECM only handle the signals from those devices/sensors.
Example of fuse directly to devices/sensors is fuse 22, 23 and 24 for ur engine,

Fuse 6 and fuse 27 are other fuses which is direct to ECM, from Front SAM.
Fuse 7 goes to the starter


ADD : The wiring diag for M273 is partially shared with M272 for vehicle connector. So do watch out at the title description. Remove what is for M272, so less confusion.

T100T

S-Prihadi,

Big thank you for the replies, based on those I've printed out the engine and vehicle PDF, will tape them together and go through the "process of elimination", it looks as though wires from one harness pass to the other (U484). I don't need to rush this.

Other notes, questions...
(i) Two f25 have been blown so far, one when the car died and a second during the initial test.
(ii) In the above you highlight an example connector "4i" pin 10, is there a way to locate connector "4i"?
(iii) I did look as the complete XEntry report from the Quick Test when the car wouldn't start, there were many other faults some of which I recognized others I didn't...
- N10/1 - Front signal acquisition and actuation module (Driver-side SAM) - that one has been there for a while.
- LIN: B38/2 - Rain/light sensor (RGLS), again been there a while, I changed the sensor but then learned it needs to be programmed.
- N62 - Parking system (PTS) - first time I've seen it.
- N62/1 - Radar sensors control unit (SGR) - first time I've seen it.
- N30/7 - N30/7 (Electronic Stability Program Premium control unit) (ESP) - first time I've seen it.
- N51/3 - AIRMATIC - no leaks assume pump to be weak, it has been there for over 50k miles.
- N123/4 - mbrace or TELEAID (DTA) - don't think I've seen that before.
What's not in the list (not sure why) is the periodic dash error msg about low oil level (mentioned above).
I've attached the Xentry print out.

Thanks again for the help,

Peter

CaliBenzDriver

Partial Recap of what we've found until now...

Main issue : Engine starts well but dies quick!

ACTIVE DTC called by :
ThrottleBody
CKP
F-SAM
ECU Low-voltage reported (burned F24?)
Fuse#24 (15A) blows with KOEO... ECU??

​​​​​​If 15Amp circuit is recognized from the schematic options soly to feed the ECU and it blows as soon as ECU fully wakes up....
This is a catch for rookies that want to change the mystery CPU box.


Unfortunately we are missing the information of what the ECU does internally with F24 power. Let's get a plan to resolve this.


I don't believe 15Amp is all to run the ECU box itself. The efficient silicone may use from 3 to 5Amps, far less than 15A... another load is piggy backed.

I think we have a chance 15Amp feeds the throttle body management, CKP is a magnetic sensor should be 500mA Max.
Unplug throttle body and CKP sensor. Does new fuse survive or measure resistance greater than 1.Ohm?

If not... your ECU is going on a surgery FEDEX trip near you.

> PLAN B:
Research specifics of your ECU CODE using Xentry. Look up "fault setting criteria" to learn what's involved in that particular F25 circuit.

juanmor40

From the Xentry report I would disconnect the throttle body and the crankshaft position sensor and recheck for the short.

From the mileage reported for the different informational (I), and soft faults (f) it seems the car has been in a cascade of low voltage , electrical issues.

The only confusion I see is main odometer reading does not seem consistent through all the modules. Has some part been recently replaced?

CaliBenzDriver

crazy numbers
When you read down the report:
battery voltage : 1.79
Engine RPM: 250
Mileage....
Are these numbers corrupted data ?

Let's make sure it's not a bad dashboard battery if any in use. It looks like ECU loosing power...
Does F24 contribute power to run ECU ? Now a possibility.

T100T

All,

Have been running around with other issues today so besides printing and taping F and M connector wiring diagrams no progress. I'm seeing references to f24 in the above, it is f25 that blows. I think things like voltages of < 2V are bogus. I will remove the throttle body and crankshaft position sensor and measure the resistance but am struggling to imagine a sensor failure resulting in a short, for that reason I'm focused on the wiring to the sensor. I've read that others have had to change the engine harness, am not sure how common ECU failures are.

Thank you all for helping me with this.

Peter

T100T

So didn't get to disconnecting throttle body or CPS but did go through the vehicle (F) and engine (M) PDF pdf files for the ECU.

So without chasing every line it looks as though the F connector diagram is mainly showing signal lines, there are some fused supplies (but those fuses aren't blowing) and there are certainly CAN devices but power isn't shown, there are plenty of grounds; I didn't see what would be general power going anywhere. I checked the pins and all are accounted from 1 to 80 (I assumed the connector has 80 pins). So I'm left wondering if the f25 with its 15A fuse is indeed to power the ECU? The diagram for the M connector has things like injector valves, and the ECU does have plenty of cooling - maybe it is a 100 W device with some margin to the 15 fuse.

Just a thought.

Peter

S-Prihadi

Don't worry too much on the Xentry recorded fault parameters, those long ones. Some numbers can be crazy... ha ha ha.
Mileage a tiny bit different between modules, I have seen it too.


Now we first must trace where are all the powers of the ECM are coming from as upstream as possible and what are the relay/s involved:



No need to worry for fuse 7, because it is drawn but it is only going to M1 starter.
Fuse F6 is not in use in my car, in your M273 it is being used by ECM, for what ? We don't know. It is from Relay J, under circuit 15. Don't worry about it.

Fuse 27 - from my DIY relay tree. For M273 it is to connector F, pin 16





======

Fuses 22 to X26 no 1 pin 5 >>> to splice Z7/36z2 >> find the devices or sensors using this power source. This fuse does not power ECM directly.
Fuse 23 to X26 no 1 pin 4 >>> to splice Z7/38z2 >> find the devices or sensors using this power source. This fuse does not power ECM directly.
Fuse 24 to X26 no 2 pin 1 >>> to splice Z7/35z1 >> find the devices or sensors using this power source. This fuse does not power ECM directly.
Fuse 25 to ECM directly via splice Z7/73 and into F connector of ECM, pin 3 and 5




The above relay tree I made it to learn and as a database to keep, on the layers of interconnection the relays are used as intermediate switch. Relay can fail, so we have to know what fuses are actually via relay.



===================

Now for fuse 25 troubleshooting .
At Front SAM it is from connector 4i pin 10. I never remove my Front SAM, Cali has








You do not need to worry about connector 4i for now.


======================

TEST 1 - Is the fuse 25 blowing because of overloading at ECM due to shorts somewhere inside ECM or at the output of the ECM ? We try to verify.

AA. Test for short circuit of wire from connector 4i pin 10 to splice Z7/73 to ECM wire harness side F connector..... to ground or cylinder head.
1- Disconnect both connectors F and M of ECM.
2- Disconnect battery negative clamp.
3- Remove fuse 25
4- Use continuity first and then refine to Ohms when beeper sounds. DMM lead positive to ECM Pin F-3 ( connector F pin 3 ) and later F-4, DMM lead negative to cylinder head metal.
While doing step 4, shake-push-pull the wire harness which leads to the Front SAM.
Resistance will be high for step 4 if any, would be few mega ohms if not OL ( out of limit ) or zero connection.
If a near true short of say 0.7 Ohms, that would blow that 15 amps fuse. At 12.5 volts and 0.7 ohms = 17.9 amps load.


BB. Preliminary test : If ECM internal components is overloading fuse 25.
1. Battery is to be connected back, like normal.
2. Remove ECM connector M, only M. The F connector is to be connected back to ECM.
3. Install fuse 25 but replace it with no bigger than 10 amps. Don't use the 15 amps one.
4. Key : Ignition ON, Engine OFF
If the 10 amps fuse does not blow, this is a happy possibility that internally there is no overload internal to ECM as when the M connector is disconnected, a lot of the working load of the ECM won't happen.

At the least do this AA and BB test first and come back to us.

S-Prihadi

Peter,

When you probe the female terminal in the ECM connector, there are 2 sizes.
The smaller one is MLK 1.2 and the bigger one is called SLK 2.8
I would suggest you buy the MALE terminal version of this, and make a test probe. The reason being, MLK 1.2 is a very fragile female terminal and probing it can cause its bite to weaken and
bad contact happen and in the end you get into intermittent trouble.

Male MLK 1.2 https://www.bmotorsports.com/shop/pr...oducts_id/3310 buy 6 to 10 pcs
Male SLK 2.8 https://www.bmotorsports.com/shop/pr...oducts_id/4197 buy 6 to 10 pcs

Use this male terminal as probe pin, insulate the main body and only the blade to be exposed.... with heat shrink as to not short anything.
The test wire is to be at least 30cm or 1 feet. Do not crow-bar the female terminal when this male terminal is inserted, hence 1 feet cable can make sure you do not shake-shake
ECM wire harness side connector. Again , I am reminding that the female terminal MLK1.2 is very fragile for its tongue inside it, so less bite in the end when you wiggle the male terminal too often.






This is their dimension in millimeters, just in case you want to use needles for the time being.


So, MLK 1.2 means the width of the flat blade is 1.2mm, but see its thickness is only 0.59mm.
The same with SLK 2.8, the width of the blade is 2.8mm, but its thickness is only 0.75mm.





If you want a safe probing wire kit, its other end is to use the safe-insulated 4mm banana plug. You can then order this kind of banana plug type test leads for your DMM.

.

S-Prihadi

The oil level sensor on your M273 is a single wire design, using ground connection when being ON or closed circuit. Switch when closed ( low oil ) the switch then grounded itself.
If it contribute say to a sort circuit, it can only do so when its wire jacket is wounded and another +12V or +5V source wire also wounded and they both "mated" at the copper strands.
I read the +5V supply in ECM is quite smart because it is a regulated power supply, it will shut off itself when shorted and do not blow a fuse.....but one will never know till we test it.


After test AA & BB done.


Disconnect battery negative clamp for Test CC and DD.
While doing test, shake-push-pull the wire harness which leads to the Front SAM/Engine sensors
Since the sensors are not removed for this test, I mean not disconnected..............
Resistance reading will be high and not likely to be OL
Any readings like 2 ohms or lower, is most likely a short to ground.


TEST CC
If fuse 25 blow again with only ECM's F connector removed, meaning M connector is connected to ECM, check below for M connector wire harness short to ground.
- Remove M connector from ECM and measure these pins in red circle are shorted to ground ?
- DMM red lead one by one to all the pins circled in red and the black DMM lead stay to cylinder head metal.












TEST DD
If fuse 25 blow only when F connector is connected to ECM, do exact same method of TEST CC to the wiring harness of F connector.
- Remove F connector from ECM and measure these pins in red circle are shorted to ground ?
- DMM red lead one by one to all the pins circled in red and the black DMM lead stay to cylinder head metal.






Good luck...............