xvvvz

Did you go here?

http://www.eclassbenz.com/acdiag

ScottyP

??
That link is for E-Class 4-digit codes..
I need the DTC code:
42 1
41 6
41 7
41 9
Where are these DTC codes?
Are these codes the same as the ODBII codes PXXXX??

vinceC

You may want to send your codes to Steve Brotherton.

If I remember correctly, the E-Class and C-Class codes are the same - you just subtract the B1 from the E-Class codes.

These are not "P" codes. "P" stands for powertrain.

ScottyP

41 & 42 DTC codes are not in the list. Still looking.

vinceC

Please pay a little more attention to the help provided so far. They are in the Steve Brotherton article (if indeed my memory about subtracting the B1 is correct - you have to confirm that somewhere - perhaps by contacting Steve):

421 Pulse module
416 Coolant Circulation Pump
417 Duovalve
419 Electromagnetic Clutch

ScottyP

Sorry, I didnt know about the B1 dropping. I was looking at the link with E-Class codes. Will pay closer attention... Found it in the 2nd attachment.

So what is the Pulse Module and where is it located?
Cleared the codes and 421 error code returned after a short trip to the mall.

Sent a PM to Steve but no reponse yet..

vinceC

I can't find any reference to "Pulse Module" or it's ref number N05 (I think) in the ETM. Perhaps Steve will shed some light here.

However, my guess is that this code search is leading nowhere. I have attached a diagnostic chart for the Pushbutton Module (N22). You can pull the module and check inputs and outputs at the connectors. There are two connectors, 1 and 2. You will have to figure out which is which - look carefully for markings on N22 itself or the connectors. The numbers on the left column are connector/pin numbers. For example, 1.8 is connector 1, pin 8. I have also attached a connector diagram - it is a bit hard to read, but it shows the pin locations on the connectors themselves.

Good luck.

ScottyP

Thanks Vince,
Unfortunately, I dont have the Pushbutton Module (N22). My module is the digital type. It uses the radio removal keys to extract and the connectors are different too.

Your second attached file is damaged and I could not open the file. Please replace the file.

vinceC

You are getting confused by nomenclature. Both the early and late units are "pushbutton modules" (and their functions are nearly identical) and they are identified by "N22". M-B has used the term "pushbutton unit" or "pushbutton module" for many years. I know you may not want to accept this, but electronically they are very similar and functionally the HVAC system is very similar. Just the human interface is notably different. The Diagnostic Chart is for your '99 "N22".

I am attaching the Connector Diagrams for a second time. I tested it before and after attaching it and it opens fine for me in Adobe 6 & 7. The forum software won't let you attach the same file again, so I had to go back to the original post with the attachment and delete the first try to get this second try to work.

ScottyP

I separated the 2 HVAC control unit only by the differences that I have experienced. My 95 had a push button system that was mounted differently and iirc had 2 large bus plugs. The 99 has one large bus plug and a smaller pin connector. From looking at the chart, it appears that the testing is done with the car running and control unit connected. Are these test for the harness testing to determine bad components OR to determine if the Control Unit itself has problems?

Still having problems with the new file. Im using Adobe 9 reader and Adobe 6 Pro. Not sure what wrong with the file.

vinceC

I'm not sure what to do with the connector diagram. It must be an issue with 9, although the diagnostic chart was created the same way. I believe the small plug, 18 pin plug is #1. If you compare to the diagnostic chart, it stops at pin 18 for plug #1 - no other pins above 18 are used. The pin numbers are on the plugs although you may need to examine them closely with a magnifying glass.

It looks like plug #1 is for inputs. In other words, those are values coming from sensors, etc. and you read them at the female side of the plug. But since you can pull many of the values using the Rest button I don't know how much value this really has.

NOTE: At the top of the chart is a note that "All values measured to ground unless otherwise noted".

Plug #2 looks like it is for outputs so you would measure them at the male side (the module side). It would be interesting to see what the outputs are to the switchover valve block (located on the back side of the blower housing under the glovebox). That is where the vacuum signal gets sent to the servos. If no signal is getting to the block, something almost certainly has to be wrong at N22.

I have to say I think unless someone else has a magic bullet, this looks like it is getting too difficult to solve on the forum. If you had one of the W202 Service CD's or were able to navigate the WIS, you could use the ETM, which has the wiring diagrams in color, the plug diagrams, diagnostics, etc. But this way just doesn't seem to be working for you.

ScottyP

I have the W202 Service CDs. Both EPC/WIS and I also have AllData. Where is all of that stuff??

As for Plug 2, Im really not expecting outputs to the switchover valve (due to being in default mode) but will validate. The problem will probably be upstream from the inputs on Plug 1 (causing the default mode). What Im trying to figure out within the WIS is the diagnosis for determining what events/sensors inputs causes default mode. Then investigate each one.

I can hear a whirling & bubbly noise coming from the dash when driving slow. Its like something is trying to startup but cant...
Not giving up yet!! Using the forum really does work for me, as I get input based on real experiences. Im very detailed oriented and this platform gives me the best possibility to identify the defective circuit/sensor/valve.

Maybe I should start another thread in the Tech Talk section as the HVAC control unit was used in multiple MB models.

vinceC

?????????

Lets try to make this easy by going to the CD. Guiding you through the WIS (I don't have pirated discs - I subscribe when I want info) will be much more difficult. By the way, in case you don't already know, EPC is the Electronic Parts Catalog.

If you truly have the W202 Star Classic Service CD Part # P-2700-202-03 (or higher on the last digits), it is in the ETM with Star Finder. Select ETM at the top of the Introduction page, select WEB ETM with STAR Finder, select Group 83 Heating and Air Conditioning from the Main Index, select 83.40-U-2000F Air conditioning (automatic) MODEL 202 as of 09/01/97 with CODE (581a) Air conditioning (Automatic).

That will take you to the specific wiring diagram for your car. Click on any component and a sub menu will pop up with a diagram, diagnostics, legend and connector.

The wiring diagram is marked like a map. The leads to the switchover valve block are between 6 and 9 on the horizontal axis on the diagram.

ScottyP

Purchased from ebay: MB EPC/WIS 06/08. Not sure of the Part number. Its browers-based and the EWA.net Intro screen has two selections: EPC.net & WIS/ASRA.net

I will try to follow your selection criteria as this software is different. Will let you know if I find the same info.

vinceC

Most of the eBay stuff is pirate copies. You want to go to the WIS and you want to find the ETM (Electrical Troubleshooting Manual).

WIS is the mega version of M-B diagnostics. The real version on the web (www.startekinfo.com) is what the dealers use. It takes a lot of time to learn.

The Classic Service CDs & DVDs are mini versions of the WIS. They don't include anywhere near as much info (and they only include info for the specific model), but 95% of the time they are exactly what the DIYer needs. They are also cheap if you compare regular subscription time on the web WIS. If I need info from WIS, I generally wait until I have a block of stuff to look up and do a 24 hr. subscription, but with the CDs and DVDs I rarely need to use WIS.

By the way, the EPC at www.startekinfo.com is free - they ask for a credit card but don't charge. It will always be current. The discs won't.

ScottyP

Found & printed the wiring diagram 83.40-U-2000F.
I havent found the ETM yet.

You are correct about WIS Mega data. It gives me lots of info and its not organized very well. Everything is organized into very long document list trees. I have a Selection window to narrow the search of documents. I have documents for My 95, MY96 and MY99 with & without Tempmatic. Very time consuming. I need to order the other Star CD set as this is very confusing.

Much easier to search by document number. So if you have the diagnostic document number, I can probably find it using the document sort. argggg...

vinceC

It is an HTMl doc - d83402000f. The number is on the upper left corner of the pdf I attached.

ScottyP

Found it.. After investigating the error code, its pointing me to voltage problem at serial port K2 on the right connector. Currently searching for this serial port description & location and any supporting fuses/relays in this power path.

ScottyP

Quick question...

Does the 99 C280 leave the factory with Aux fans up front of the engine bay?

vinceC

No. The V-6 W202 has one big electric fan mounted behind the radiator. Also, note that there is no engine driven fan. The speed of that fan is controlled by a module (N65/1 - AIR Control Module) in the left wheel house forward of the fender liner. That module is linked back to N22 because the load on the HVAC system will be a factor in cooling requirements.

I like this system better than the earlier system. It is simpler and much quieter and without the engine driven fan there is much more room to work on the belt, water pump, etc.

ScottyP

Now this is starting to make sense. The code is for problems with N65/1 Air Control Module. which is causing the default mode in the HVAC system. I hate that MB has tucked equipment in both front wheel wells but I will remove the tires and find the N65 module & the vacuum chamber (in the pass wheel well).

Agreed, I like the extra room and the newer design too. Those old aux fans were very loud in the summer heat but did an excellent job in traffic while efficiently cooling the engine on those hot, humid summer 95+ days. How does this single fan system perform in the summer?

vinceC

I find my '00 with the single fan runs at a more consistent temperature in the summer - about 95 degrees C on a 95 degree F day. The '95 cycles up and down more.

I had a problem with the N65/1 on the '00, but N22 worked fine. The problem manifested itself in the warmer months. In stop/go traffic the A/C capacity would drop at a stop because the fan wasn't increasing in speed enough to meet the A/C condenser requirements. As soon as the car started to roll and there was some additional air flow the A/C would operate normally.

ScottyP

Test failed for N65/1 at the N22 #2 harness pins. So, Im assuming my Fan Control Module is bad.
Searching for a procedure to test the actual unit to determine if its bad wiring or the unit itself.
Any ideas?

vinceC

I searched and can't find any diagnostics for N65/1.

It might be worth checking the plug connector at N65/1 for corrosion before replacing the part.

Question - does the radiator fan run? As a confirmation of the pin test you could try blocking air flow to the radiator with a piece of cardboard, set the A/C to LO and see if the fan speeds up. It might be hard to make it happen this time of year, though. Perhaps if you can do the test inside a garage - door open of course.

ScottyP

Yes, the radiator fan runs. At idle and warm, the fan moves very very very slow...
If I select the Automatic & Recirc HVAC buttons, the fan speed up to a much higher speed. The AC compressor is squeaking and then shuts down after 5 mins or so. Then the compressor smokes.

Im having a few discovery issues here and still havent pinpointed the actual HVAC problem yet. Tomorrow (Sat) morning, Im removing the front wheels to test & investigate. I will post results. I was also unable to find a test procedure for the radiator fan control. Its an expensive part too.