92 300TE Cruise Control nothing left to replace! - PeachParts Mercedes-Benz Forum

MCallahan · #1 05-27-2018, 09:56 PM

This is driving me insane. I have got everything working on this car except this damned cruise control. Spent today messing with it. Checked the 14 pin plug to make sure it has 12V coming in and the steering column switch and brake switch was good. All checked out. Re-soldered every single point on the amplifier board. Installed a new actuator when I replaced the engine mounts. Swapped the speedometer Hall Effect sensor off the parts car today. Still NOTHING. Doesn't even try to engage. The ONLY thing left to try is another amplifier unit, but the parts car is a 93 300e M104 with ARS, so it's not the same as my 92 300TE. Anybody got an amplifier?

ah-kay · #2 05-27-2018, 11:24 PM

What makes you think resoldering every joints would fix the cruise amp? This is the most likely culprit. I would swap in another one. I swap in 190e cruise amp for all my diesels and they work perfectly. Give it a shot with another amp.

MCallahan · #3 05-28-2018, 12:09 AM

See my post, asking if anybody has an amp. As for the resolder, about 90% of folks get it working with that, so it was worth a shot.

ah-kay · #4 05-28-2018, 12:16 AM

I am the 10% then. It never works for me. I would put the 93 300E amp in to give it a try. Nothing to lose.

MCallahan · #5 05-28-2018, 01:11 AM

The 93 is an M104 engine with EFI, has NO amp. It runs off the ECU.

MCallahan · #6 05-29-2018, 08:47 AM

Ok, this is weird. The cruise works, unless I cancel it with the brakes. If I turn it off and then hit the brakes, it will reset and run fine. If I hit the brakes without killing the cruise via the steering column switch, it will not reset until the ignition is turned off and back on. I have also not been able to get the resume to work, just have to reset the speed.

Diseasel300 · #7 05-29-2018, 01:42 PM

Send it to JamesDean (Kris Rose) for analysis and repair. Not only can he bench test it, but he can often fix what's wrong. The one in my SDL would set or cancel, but that was it. Would not decel and would not resume. Often after setting the speed, it would "run away" then become permanently cancelled until the power was cycled. The cruise amp was bad, likely one of the digital logic chips had failed. Both he and I poured over that board and never did find the problem. He rebuilt a core and sent it back and been working flawlessly since.

His website is here: Overview

MCallahan · #8 05-29-2018, 01:56 PM

Cool, thanks. Sounds like mine has almost exactly the same issues as yours. As I said above, saw his posts from 2012, but didn't know if he was still repairing them. May get another one and send him both of them, so I'll have backup.

MCallahan · #9 06-01-2018, 12:00 AM

So on the way home tonight, it works flawlessly. Sets, acc, dec, off, resume. Weirdness abounds.

Diseasel300 · #10 06-01-2018, 09:05 AM

Ah, the wonderful life of troubleshooting Mercedes electronics! I'm convinced that no toolbox is complete without a rubber chicken and some sort of offering...

MCallahan · #11 06-01-2018, 12:44 PM

Considering my last experience like this was a 300ZX Twin Turbo, I'll take it. At least when I fix something on the Mercedes, it stays fixed!

bigpanda16 · #12 06-07-2018, 03:54 AM

Have you tried a new brake switch?

MCallahan · #13 06-08-2018, 12:09 AM

It's working now, except resume, which I can live without. No time at the moment, but I may swap the brake switch out of the parts car just to see if it makes a difference.

MCallahan · #14 06-14-2018, 02:49 PM

Maybe you guys can clarify... Cruise seems to work perfectly now, as stated above. Don't know how or why and don't care! Only thing still acting up is the resume. If I slow down and cancel the cruise using brakes or the lever and stay near speed, resume will work perfectly. If I drop below about 40mph, the resume will not work, even if I speed back up before activating. So, does the resume not work after a stop or when dropping to a certain speed? It's not really an issue, just curious if it's working properly or not.

Diseasel300 · #15 06-14-2018, 04:01 PM

I'm not sure if the Mercedes CC circuit has a minimum speed to set, but the resume function should work at 30 or above (I've never set it or resumed below 30) whether or not you've stopped. If you've shut the car off, the resume setting will be lost until the CC is set again.