W124 - Fault codes

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ModMan

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Mar 27, 2008
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93
Location
Midlands
Car
Soon to be a 2013 A Class
On my 1992 300TE 4matic there is an 8 pin diagnostic port next to the fusebox.

I am trying to read out the codes to find out what the big yellow triangle and 4matic lights are on for.

Going by the guides I have found, there are 2 types of diagnostic readers I can make. One has 2 pins, and one has 3. It looks like the three pin one is only needed if you have the 16 pin diagnostic port, is this correct? If so, tonight I've been trying to read the codes (Using a voltmeter, I'll buy an LED tomorrow) but am not having any joy. (I don't get any reading on most of the ports.

My undestanding is:
Pin1 = Ground (Always have the negative of your fault code reader to this)
Pin2 = Not Used
Pin3 = CIS-E (Fuel injection)
Pin4 = Diesel system?
Pin5 = 4matic
Pin6 = SRS
Pin7 = A/C
Pin8 = Not used

I went through and got a few 4matic errors but the voltmeter isn't good enough to get the codes as it fluctuates a bit. So I cleared all the codes, but the 4matic light is still on.

I have been doing this with the ignition in position 2 and not started the car once.

Just to add, it appears only Pins 1,5,6,7 are hooked up as I can only see copper contacts in those ones.

Any hints and tips?

Cheers, Daniel
 
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I'll up my post count by another 2 posts then (1 after this) so I can use the PM function! :) Thanks Bruce.
 
Damn, looks like Grober doesn't accept emails on his profile. So I'll just bump this up :)
 
Hey Graeme - So it looks like I need the three pin diagnostic connector then. Excellent, I shall make one of those tomorrow. I've been reading all over, including the US forums saying the dash light may flash too (Mine doesn't) Thank you!

I assume the car needs to be running for this?

Is this related to the big amber light too that's on in the middle of the speedo do you know?

Cheers - Daniel
 
If its the orange triangle that's the 4matic light which should flash on and off signifying the intervention of the system but should not remain lit all the time under normal circumstances. On some fault code reader systems the ignition should be on although I'm not sure if this is strictly necessary for stored fault code reading? As part of the fault code process it may be necessary to cancel any fault codes found after taking note of them and then take the car on a short test drive to see if they return? Bit of trial and error required here I guess. Quite common are problems with the ABS wheel sensors [ used by the 4MATIC SYSTEM] either the sensor dirty or shorts in the wiring. these may cause the 4matic light to lock on and only extinguish when the ignition is witched off.
ps you may also find the ABS/ASR warning light comes on also in the light row below the speedo tachometer gauges
 
Well I'm getting somewhere.

Basically code 10 from the 4matic. It's not the OVP as that was replaced last week. So either stop lamp switch (Is this the one for the brake lights as it appears to work ok) or something to do with the rear diff ... time to google.

Just a quick question. When i clear the code, the 4matic light goes off but the check engine light is still on, how do I read that code? Also I needed to get the 4matic code with the engine running. about 30 seconds after clearning the 4matic code 10, it comes back (Car idling on drive) and there's a click under the car somewhere.

Dan
 
Low voltage supply will often trigger the engine warning light. The OVP feeds the idle speed controller the engine ECU and the ABS system[ and 4matic by association]
Did you fit a new/correct OVP? I would deffo change the brake pedal switch [ used by both ABS and 4matic ] for all they cost. I would definitely check some supply voltages at this point-- could be an alternator fault or some wiring problem or a defective module pulling voltages down for units that share a common supply. It sounds as if what's happening is that at ignition switch on the various modules go thro their self test routines and when they find low supply voltage are flagging up an error.
 
That sounds very possible actually. The original battery when i got the car was knackered but before I spend £80 on a new one I am using a spare one I had in the garage. It's too small but starts the car ok however it goes flat when left for a few days. I was just assuming the small battery was knackered too.

I should just splash out on a new battery, new switch and then troubleshoot as you suggest. Time to go battery hunting!

As for OVP - Yup, it was def the right one. Same part number and looks the same as the old one. I bought it from Wunderpartz on eBay.

Thanks again. Dan
 
Just to update this thread.

Bought a new battery, errors still remained.

Bought a new brake switch which arrived this morning, I then cleared the 4matic light and drove around for 10 mins. It hasn't come back on so it looks like the switch was the fault. Before, if I cleared the light, it'd come back on within 2 mins. So I am smiling now!

Now, just need to fix the rev counter. Also the big yellow warning triangle light is still on. Any suggestions on how to read that code? My car doesn't have that CIS pin in pin 3 on the diagnostic port as i though that's how I would read it.
 
other 4matic issues

Guys

I found this thread whilst Googling.

I recently bought a 300TE 4matic and whilst it's in really nice, clean, rust-free condition body-wise the 4matic is playing up. The triangle in the speedo for traction control goes out as normal, but the 4matic light is on all the time.

Not only that, but when I built a code reader as per the thread, whilst I can pull codes from pin 7, the led just stays on all the time with pin 5 (4matic) of the 8-port diagnostic socket. The bulb had been removed from the 4matic light so I suspect that someone has hacked the system about in the past.

The controller unit is present behind the battery and it doesn't look as if anyone has hacked the loom about. There was however no fluid AT ALL in the hydraulic reservoir and although I put some in, the level didn't go down (as if the system is blocked off or the pump is u/s.

Any ideas where to start?? Does this mean dead control unit?

cheers

Dave
 
Hello Grober
I have a question regarding 4matic problems, I am considering buying a w124 300TD Turbo with 4matic, it was been in storage for five years, and when I started it the parking break warning light was on and the 4matic warning light was also on, a bit of break fluid fixed the parking break warning, but the 4matic is still there (orange warning light, not the yellow triangle) another thing that is wrong with it is that the right front wheel break is rusted in place and that wheel get very hot after a few minutes drive, so my question is?: can any of the above be the cause of the warning? Or is it more likely that long time of inactivity is messing with the sensors?
Thank you for reading my post, kind regards Mads
 
These systems were fairly primitive and can be upset by a dragging front brake. The 4matic hydraulic controller uses signals from the ABS unit/sensors to operate so its entirely possible the 4matic warning light is on for that reason. That front brake needs to be freed up to check the correct operation of the system.4matic1.JPG 4matic2.JPG
 

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