K38 Relay on 124.022

[sicelo]

I have a non-starting 1994 E220 (124.022). This will be a long post as I try to include as much information as I have:

• Car had original Mercedes Benz alarm early in its life as a VIN check indicates
• VIN check also mentions infra-red system. The is no single indication that this ever existed on this car. I only got plain key from previous owner, and there are no IR receivers on the doors
• car also has convenience module (which i only discovered while doing the work described below. i don't know if this is working, or if it's of any use. windows don't close automatically)
• the Merc ATA must have given problems somewhere along the line, and previous owners then installed after-market alarm (Shurlok ER150). this alarm would run the battery down. Original Merc ATA must have been thrown away
• when i got the car 5 months ago, battery ran down within a week of ownership. Took it to the garage, where they disconnected the Shurlok alarm, and battery problems stopped
• car started running the battery down again. check via fuses indicated that circuit protected by Fuse C draws about 60mA alone when car is locked, even though there is now no alarm at all in the car
• So I decided to try reconnect all wires back to original status (as the harnesses all still exist). this was also just to bring my W124 to as close to 'virgin' state as possible, and was hoping to install another alarm system in the future
• result was that interior and trunk lights operated correctly (improvement), and the central locking now works with both passenger and driver doors (was only driver door before)
• unfortunately, car does not start anymore. fuel pumps run, and all lights come on
• i had expected this, because i had previously researched this, and 'believed' i would also have a K38 relay behind instrument cluster, which i could then jumper
• for the life of me, no K38 relay or other type relay to be seen behind instrument cluster
• all my fuses are fine

So I'm stumped now. I'm happy that everything else seems to be working better than before, but now I almost don't have a car.

Starter does not even attempt to turn. Battery is not flat.

So my question is, on E220 (124.022), where is the K38 relay located? My engine uses the HFM-SFI system, and I do have what appears to be K1/4 relay in the relay box behind fuses. (Page 12 of http://www.w124performance.com/service/w124CD2/Program/Chassis/80-400.pdf) Is this what I would have to jumper in my case? This one also suggests a K27 relay might also be involved..

If anyone has wiring diagrams specific to this model, these will be most appreciated. I do have the WIS and EPC, but these do not contain wiring diagrams (or i can't find them)

I think I will remove the dash tomorrow to see if the K38 relay did not perhaps 'fall' inside the dash cavities. Will also have a look at OVP (I hope this isn't the problem)

If you have other suggestions, I would be most grateful

 

[grober]

Fuse C supplies a lot of the central locking system including the convenience module and any alarm system. It might be helpful to trace the source of your current drain as this might lead you to a faulty control unit. The implementation of security/alarm systems varied according the market-- the W124 PERFORMANCE SITE will refer to American market cars. All you can do is methodically work through your car's electrics to find the fault. One useful thing to do would be to check that the fuel pump relay output is activated and the OVP relay is powered up on ignition switch on.

 

[sicelo]

Will do that. Forgot to also mention that having repaired the connector for the MB alarm (the one with two connectors, with 8 and 14 pins respectively), pin 1 indicates as always grounded, while Anti-theft alarm and K38 relay - Mercedes-Benz Forum would suggest that it should not (my color codes correspond exactly with his, except I don't have a pin 3 on the 14-pin connector). I will therefore have to investigate this short and see if that's not my problem.

 

[sicelo]

Found the bugger!!!! K38 relay
Too bad I had to remove my cluster for nothing, as in my car, the K38 relay is on the passenger side, near the fender. It's hidden just under the big tubes for the ventilation system.

I still have the 60mA in circuit 30 protected by Fuse C. At least I have a running car now, and other stuff works properly.

 

[boomtings]

Well done in finding the relay. I was searching for it previously but never found it.