Thanks!

@@mygermancars7264 1 problem down and many more to come 😂....but at least you have the m103 engine. Short of a completely seized engine, the m103 will continue to run as long as there is fuel, air, and spark....Can even run it without an ecu if you needed to. Just make sure you stay on top of the tranny though....the notorious B3 brake band (reverse) seems to be the first to go 90% of the time. Ugh!, I remember having to always park on an incline or pull forward through a parking spot so I could either free roll out of the space or just drive out without going in to reverse. Did that for about a year+ until I got a new transmission 😞

Update. so after studying the schematic I think your right, my wire colors are the same! and looking at a few other schematics looks like the wires all need to go down in connector, will try to change them this weekend, will do a video and post, so weird? who would have done that and why??? thanks for the help man!

@@mygermancars7264 👍. Happened to me a few times when changing some of the brittle connectors out in the engine bay. Ended up swapping around pin 1 and 2 not realizing that they are different polarity and ends up throwing everything off.

Can’t wait to try it out! It’s my son’s car and needs it for work this week, maybe Saturday, he loves that switch on his dash, says it brings temps down in under 30 seconds, trying to figure out if we can keep it for the over ride function?

Did not fix original problem, after a week of diagnosing I got burned out, my sons been driving this car for 12 years, it’s been a pretty good car without to many issues, he bought it on eBay for $3,800, arrived with a blown HG, so I fixed that, machine shop etc. Last 5 years it started having this overheating problem, only during summer time, last summer I replaced entire cooling system 1K, did the citric acid flush to block thinking oil scaling reducing flow, not much came out, also installed a new HG due to oil leak at #6. Trouble shooting the HS fan issue, sensor sends signal to CCU, schematic shows blue/ grey wire from sensor is input for CCU, that’s the main trigger signal to turn on fans HS, good continuity on blu/grey wire, sensor new, output from CCU is brown/grey pin #13 that fires HS fans, continuity good from wire to fuse box relay socket, with car on CCU is outputting 12v on that wire to relay socket, but still no HS fan? Here’s what’s strange, at pin 13 wire I can apply 12 volts with power probe and fans come on? Or I can apply ground to wire and fans come on? Bizarre as hell! So for now installed dash switch using only ground signal and can activate fans. See what I’m up against? Schematics shows K10 and K9 are wired in parallel, that may explain the confusion. Now testing the relay sockets at fuse box, with key off some sockets test as grounds, turn key on and they test as +12 ??? That’s weird as hell! Gave up for now, besides next spring would like to retrofit to new electric fan setup, lose fan clutch deal.

@@mygermancars7264 Did you move all the wires up by one pin on the connector like I mentioned? I'd have to check, but blue/grey wire for MB at that era were typically for light illumination. Sounds like you might have had a simple problem with a simple fix that you could've compounded if you got one thing wrong now, despite the troubleshooting, nothing is lining up. Kinda like buttoning up a shirt and missing one hole, everything is then completely off until you go back and fix the one thing. Super frustrating. I'm sure all the components all check out perfectly and within spec, even when bench testing. I remember I replaced my head gasket because of something completely dumb. My coolant reservoir had a crack so I put on a new one and shortly after my car kept over heating. I replaced the coolant cap and same thing. Coolant flowing out of the wheel well tank and temp spiking to 120C after 10 minutes of driving. Symptoms all pointed to exhaust gases going to coolant so I replaced the HG. However, that was not the problem. I actually ended up accidentally connecting the hose from the thermostat housing to the nipple just below the radiator cap on the reservoir and the hose going to the over flow tank to the other nipple when I replaced the reservoir. 🙄 such a simple mistake could've cost thousands had I not been able to do the job myself.

@@brittanywright9646 Move the wires ? no, did not and don't think that would work, the wiring is still factory , each wire is cut to a certain length to fit the connector, about 15 wires in it, would be hard to put the lid back on for sure, but every schematic shows pin 11 brown /grey is the trigger wire for HS fans, mine is pin 13 brown /grey, then again could not find exact schematic for 1991-1992, just 1985 to 1990, so figure they did revisions, hard finding 30 year old European schematics, probably in Germany they would have it. The only things I can think of are, could be a grounding issue since my switch makes them work using brown ground wire borrowed from rear headrest switch, or ,I have found some rat/mouse droppings in engine bay, maybe they chewed a wire somewhere? or , when we got the car years ago it had a few interior electrical issues like illumination lights not working, fixed that at instrument cluster, or, someone cut 5 or 6 grounds behind radio unit and under consol , could have been some idiot installing stereo /amp setup, I fixed the cut grounds. See why I give up lol.

I did the same exact thing on first HG job, had the EX tank lines reversed lol

@@mygermancars7264 I have every schematic for the 124 for about all 40- 50 model variants from about '86 - '95 that's why I told you to move the wires.

Yes, its new

When all is said and done, more will be said then done. Lol! Thanks for sharing.