Hello

I just picked up the car today. It drives pretty well (while in gear ams accelerating) and everything seemingly works on it. Only issue that’s cropping up is the abs light will come on a few minutes into a drive and the car will die if I slow down to under 10 mph with either the clutch in or if I move it out of gear and coast. While accelerating or changing gears everything is fine. Car only has 39k miles, no blown fuses. I haven’t had ample time to investigate it deeper but since I’m new to Mercedes manuals I was wondering if there are any things I should check or tricks I should know about them.

much appreciated and can’t wait to get into the MB world!

-J

 

First, I think you must look at the simplest possible cause.. is your battery ok?

 

hello

The battery seems fine. Voltage output is normal and the car starts without issue.

jeff

 

When ABS MIL is lit it throws a trouble code (DTC). Instead of guessing acquire/make a Mercedes blink code reader. One of the most common issues with ABS is faulty brake light switch. But as said read your DTCs.

Welcome to the forum!

 

thanks!

yep I just ordered one of those code readers

hopefully its an easy fix

 

Code reader still on the way but here are some more details about the ABS light. The light comes on only when spinning the front left wheel forward (the light doesnt come on spinning the passenger side) both speed sensors have been replaced and it did not change the issue of the left wheel rotating triggers the light. The wiring loom from the sensor into the engine bay looks fine no sheathing degradation.

 

I've had a 300SL for nearly over 20 years and have MANY DIY fixes for many gremlins on this car. The ABS flashing and car running erratic [for me . . . ] was caused by an old OVR [over voltage protection relay]. Replacement remedied this issue. The OVR relay is located under the hood, on the passenger side under the plastic cover [top left side]. Do a search here and see actual location pic.

Good Luck.
Hz

 

Thank Hz!, I suspected the ovp relay as well. The one currently in the car is a URO products one, while the two fuses are not blown from my time with 911s I know that brand is really hit or miss. Ive ordered a different brand one and will try that out before bringing the car to a specialist for diagnosis.

 

A new ovp relay didn’t fix the abs light. It comes on consistently from the driver front wheel spinning or moving forward.

 

Firstly, this sounds like a very nice find. Congradulations!

What brand OVP did you get in the end? It needs to be Mercedes or KAE. I would not bother with other brands.
Your ABS light if only triggered while driving is most likely unrelated to the engine stalling "IF" it is not OVP related as both functions rely on a correctly functioning OVP.

I believe your model year is the first year in which Mercedes separated the emissions and idle controller in to two separate boxes. So I suspect the OVP needs to be for the correct model year.

This being said I should ask: Is this car a manual swap or factory manual?
I happen to own a factory manual '89 190E/W201 so I maybe able to help you with the stalls since I've seen it all with my car (original owner)

If I were you I would first rule out OVP issues, they can even cause the stalls.

Have you measured the system voltage (past the OVP) on the X11 diagnostic port? You need to see the battery voltage there.

At some point you will need to explain what you mean by spinning wheels and triggering ABS light and by that I mean describe the procedure.

- Cheers!

 

hi thanks for the help! Answers to your questions below

The brand ovp I got is Meyle (is it possible both the replaced uro ovp and this meyle one is bad?) how would I get an ovp that’s correct for my year? (1990) should it just be a new genuine mb?

the abs light only comes on when driving forward and to describe what I was doing to trigger it in my garage. I jack up the front of the car, turn on the ignition so its running then spin the front wheels by hand the abs light comes on each time spinning the driver side wheel and does not come on spinning the passenger side.

it is a factory manual trans

by measure the voltage at the X11 port I’m guessing you mean with a voltmeter touch ground and stick the positive into the number 11 port in the code reader ports?

if that’s the case here are the voltages I read doing that

car completely off -> 4.5 volts
car ignition in position 2 -> 4.5 volts
car running -> just over 6 volts

I just got the code reader today and I’m getting a 17 pulse code on port 8 (crankshaft position sensor faulty)

thanks again for the help

 

LVJEFF>> The brand ovp I got is Meyle (is it possible both the replaced uro ovp and this meyle one is bad?) how would I get an ovp that’s correct for my year? (1990) should it just be a new genuine mb?

I would go down to the dealer and get the MB if I were you. That is the only way you will know it is made for you car and will last. URO makes parts that are not always a fit for the model year. It is a hit or miss and the quality is suspect. Same with Meyle IMHO.

LVJEFF>> the abs light only comes on when driving forward and to describe what I was doing to trigger it in my garage. I jack up the front of the car, turn on the ignition so its running then spin the front wheels by hand the abs light comes on each time spinning the driver side wheel and does not come on spinning the passenger side.

This procedure, even though I never tried it will trigger an ABS light in every car unless you were spinning the rear wheels at the same time at the same speed. If all 4 wheels are not spinning at the same speed (within 3%) the ABS light will come on after some time. I'm not sure how long the timer is for this. The system has to first establish all wheels are same speed before triggering ABS an if it thinks something is wrong it will warn the driver that it has disabled ABS because it could not establish a working system.
it is a factory manual trans

LVJEFF>> by measure the voltage at the X11 port I’m guessing you mean with a voltmeter touch ground and stick the positive into the number 11 port in the code reader ports?

No, the X11 should be a round connector near your EZL (ignition control unit). Perhaps post a picture of your EZL area because I'm not familiar with your model. I assume it is a KE-Jetronic emissions? But it is a 24V so the ignition could be quite different.

Also, the code of no CPS signal is of interest. Reset that an see if it comes back. Also measure it's resistance (at the EZL coax connector) an see if it is within spec. It maybe on it's way out.
Although a CPS malfunction is generally fatal meaning once it fails the car will not start until the engine/CPS cools down.

I hate to report to you that your Ignition Control Unit might just be one of the unicorns. Meaning you will have a hard time replacing that because they fail prematurely and so few of them were made. Other models/years go forever. Post a picture of it here, hopefully I am wrong.

- Cheers!

 

Here is pic of the ezl part no. 0227400734






I’ll get a genuine ovp relay. The crankshaft sensor code is a red herring. I’ve read it will trigger when the engine is off and that’s how mine behaves. No code if the engine is running and a code appears if I read it when it’s off.

that makes sense about the abs light triggering when I spin the driver wheel and nothing else. But wouldn’t it also trigger by spinning the front passenger wheel? I can spin that one for endlessly and it doesn’t trigger. If I spin driver side it will trigger in about 20 seconds.

again thanks for the help
jeff

 

Hey! you have the exact same color as my 1989 190E, Signal red I presume for the 1990 year (tone was changed between 89-90). I still have not figured out why mine is a '90 paint color but that is a whole different story. Yours is super clean under the hood like mine. Yours is a rare find indeed....

LVjeff>> that makes sense about the abs light triggering when I spin the driver wheel and nothing else. But wouldn’t it also trigger by spinning the front passenger wheel? I can spin that one for endlessly and it doesn’t trigger. If I spin driver side it will trigger in about 20 seconds.

This all depends on the electronics. I do not know how it is designed. There could be a master-slave where everything is compared against the driver side or passenger side wheel. And the 2 wheel spinning may have a different out come. We know at least one wheel has to spin for the system to turn on, maybe it is the driver front. That would explain your outcome. When you spin the passenger only the system is not even on perhaps. Unless someone else is willing to run the same experiment you will never know. I would do it for you however my car is currently un-operational and my manual transmission is coming out for a major overhaul and seal replacement. It did go 200K+ miles so that is not bad and I'm due for the very first clutch overhaul. 200K+ for a cutch, that is not too shabby either.

The X11 port is the round one to the right of your EZL. Unscrew that and you will see a few pins. 2 is ground, 3 is Duty cycle (very important). Read up on that and either 5 or 6 is your system voltage at your ECU. Measure that with the car running and not. Should read 12.6V not running an ~14V while running.

I will have to study your EZL part number but you should also do an internet search. I have the impression it is NOT the unicorn I was afraid of. That will be very fortunate for you.

- Cheers!

 

Thanks for the info and explanations I’ll get those voltages and report back. And I’ll read up on that duty cycle pin. The car is super clean I dig it a lot.

cheers

 

Yeah, take care of that car, it is a gem and try and not use aftermarket parts if possible. Check for parts at the dealer first and if they do not carry them try the Mercedes Classic center in Southern California next after going aftermarket.

BTW, there is another important signal there on the X11. That is pin 4 (to pin 2 reference). I believe that is the CPS signal to the EZL an that needs to be glitching as you crank. That is another way to tell if the CPS is good. But honestly at that low mileage the CPS will most likely not be your problem. Mine is still original at 200+K miles. They do go bad but not that early.

 

X11 voltages

pin 6 when engine off 12.11
pin 6 when ignition pos 2 11.9
pin 6 when engine running 13.05

pin 5 when ignition in pos 2 11.9
pin 5 when engine running 13.05
(Pin 5 only gets voltage when ignition in 2 or engine running)

so does that seem like the ezl is ok?

thanks
jeff

 

Those measurements can not vindicate the EZL, they only assure us that the EZL and ECU is powered up and running. So perhaps your OVP is ok in the first degree.
It appears to be giving out a timing signal because that voltage is lower than the system voltage.

Your voltages are a little low, assuming you did not have a lot of equipment running (like a blasting stereo, AC, headlights, aux fans, HVAC fans etc)
They appear to be about 0.5V lower than they should be. Keep an eye on that. I usually have a USB charger in the car plugged into the cigarette lighter that has a voltage meter on it.
Your running voltage should always be close to 13.5V when nothing else electrical is on,

Your EZL is more complicated than the regular 12V EZL's because it has many more signals coming out of it for the 24V operation. I have no way of diagnosing if the EZL is working 100%.
But remember that when your EZL malfunctions it is generally that the car would not even start because the timing signal is not being send to the coil. So if you have a no-start in the future you should question the EZL and take these measurements.

Now there is a fault case in idle control that is specific to or at least amplified in manual transmission Mercedes of the KE-Jetronic era. Most owners in NA will not be familiar with this and I have never seen explanations (other than my postings here and there in the past) on why this is the case.

There is a fault case that was inexistent when these cars were new and they had perfectly new and operating OVP's. It only happens when a manual transmission is put into idle by depressing the clutch and the engine is going from running to idle instantly. And you can imagine it happens quite frequently in a manual transmission and it can even happen in auto but the car is always in drive and hardly ever in idle until you come to a stop. And that is generally a slow process in an auto an the car's engine is being assisted by the auto transmission delivering power to the engine via the wheels and the transmission. This is absent in a manual transmission car and the transition happens many many more times than an auto.

So the fault case is:
If the OVP randomly cuts out and you have a manual transmission and the cut out coincides with the OVP turning back on at the exact time when you are shifting the car, It will stall because the idle controller can not respond to the sudden turn-on in time before the stall. If this get's bad enough the car may even just stall when idling and right before it the idle flutters a bit, goes up and down and it stalls. Sometimes the driver notices this and presses the gas pedal before the stall and the car recovers for the sole reason that the driver took the car out of idle by pressing the gas.
This case can not be tested or diagnosed because it happens very randomly. You can test the OVP but it will look perfectly fine in a DC test.

All this is probably more than what you need know at this point in time but may help you in the future.

This is why I advocate for either MB or KAE OVP's because those appear to last at least 10 years before showing these signs (particularly for a manual transmission car)

Not every stall is what I described above. Just make sure that the issue is not your OVP before throwing parts like IACV, EHA, Ignition components, etc etc at the problem.

Your idle issues maybe entirely different. All I can say is that in the 33 years that I have owned my W201-manual the only stalls I have experienced were:

(1) Fuel pump/fuel pressure due to weak/cutting out fuel pumps (FP life ~100Kmiles, if the car is regularly driven, could be considerably shorter if the car sits for long periods)
(2) OVP case I mentioned above

And I have never witnessed the one below because my car has always been cared for but I know it happens to neglected cars:
(3) Intermittent ignition (Distributor cap/rotor, coil,EZL) issues.

Since your car appears to be cared for and so young in miles I think the ignition woes are not likely except your EZL due to it's complexity is always suspect because it is a known failure component.
Unfortunately I have no experience with your EZL so can not help you there other than just giving you a "heads up" on the EZL.

- Cheers!

 

hi thanks for all the explanation and info, it’s incredibly useful.

To the voltages I posted, they were recorded with nothing else running on the car (stereo, hvac etc) they do seem a tiny bit low like you said so I’ll keep and eye to it. The car starts instantly cold or hot every time and when I do use the accessories they all seem fine. The car accelerates and drives well enough.

The stall will happen only when I’m slowing down depress the clutch and am turning into a parking spot. I went out all day today (drove around for 3.5 hours) to reproduce the stalls. It happened twice only when slowing and turning into a parking spot and depressing the clutch. Quite bizarre.

as for the abs I got a hold of a working brake wiring harness from another r129 I’m going to swap it in with my left side one and see what happens there.

here’s the work I’ve done so far on the car

New fuel filter, fuel accumulator, plugs, wires, rotor, distributor cap, ignition coil, ovp, brake switch, engine and cabin air filters. Camshaft position sensor, both front speed sensors and a voltage regulator all parts MB or oem except the ovp (meyle)

the car really does run great minus those two stalls and that bright Orange abs light

thanks again
jeff

 

Your random stalls for a manual transmission, and the fact that one other member mentioned ABS light issues with a defective OVP do point to the OVP more than anything else.

Particularly since everything else seems just fine.

Let us know how it works out with the Mercedes OVP made for your model.

It will also be interesting to see if the new ABS sensors will do the trick for the ABS light.

 

It seems genuine MB ovp relays and even KAE relays are no longer available or at least back ordered everywhere. My choices are either uro, vemo or keep the meyle one i have or go used MB on ebay.

 

That is very disappointing and frustrating in a major way. Did you try the dealership?
What are the KAE and Mercedes part numbers?
Have you tried Mercedes Classics? Send them a message if you can.
This is a consumable part, I'm surprised Mercedes NLA'ed it already. I know many parts are NLA, and this happened in the last 2-3 years.
I have a super parts guy at the dealership I bought my car from, I can see if he can find it. Some dealerships may not care and not ship from Germany.

Send me the part numbers and let me see if I can help you.

As for the EBAY used ones, you can go that route for a genuine MB (or KAE) since the OVP date code is printed on them If it is less than 5 years old, I would buy one and test it out.

 

Pelican Parts carry the KAE OVP's. See if they have your part number.

 

For my car the KAE ones arent listed just the uro, meyle, vemo and MB (discontinued) here is the MB part number -> 201-540-374-5

do you have a link to the KAE one youre seeing?

Thanks
Jeff

 

That is disappointing, they had it listed (the same part number) just a day or two ago, but clearly the KAE brand is NLA everywhere.
So the Mercedes Siemens and KAE is out of the business it seems. And your part numbers is the same as mine so there is really just one part that works across the '89-90 spectrum, all models.

Now there are 4-5 aftermarket brands, I'm not sure which one is dependable to be honest. Only time will tell.

I actually grabbed an extra used Siemens one from the junk yard that had a recent date code. Threw it in the trunk in case mine goes bad. You can go that route as well.

Or you can still Ebay a used one but make sure the date code is recent. You do not want a 20 year old OVP.