I love your videos keep them coming
Be sure to post the one of your kE jetronic tutorial

 

I love your videos keep them coming
Be sure to post the one of your kE jetronic tutorial

the main problem on cruise controls on those cars was the actuator under hood that had a too low resistance , that would damage the controller.there is a ohm value for that motor 10 to 22 ohms at pin 3 and 7 for a 12 pin plug , and 7 and 10 for a 14 pin plug . if any body interested on how to test a dead system with a voltmeter and without the MB tester , will post it .

 

Yes please Alain. In the DIY thread if you like.

 

not sure what the DIY TREAD IS , this is for the 14 pin plug .12v at pin 1 at 8 when braking , signal at 11 with rear wheel spining , ground at pins 12 and 14 .switch will give power at pins 4 6 2 3 , when moving to all 4 positions .check sleeves for looseness with a old male pin or drill bit of same size [ tool ] .ohm value at pin 7 and 10 , should be between 10 and 22 ohms . to test actuator under hood , put 12v to pin 4 and 7 , ground 5 , the motor will run but lever will not move , ground pin 6 , lever should move , remove that pin 6 ground , the lever will snap back . i used to buy recon electronics from PROGRAMA , had good luck with their stuff .pin 14 plug was more popular then 12 , 12 was for older cars .

 

Chiming in because my cruise does not work as it should. And eventually I’ll need this thread

 

this test is for dead system , one that is not working right is more difficult .first you check the sleeves at the cruise control module [ amplifier ] loose sleeves will create intermittent problems .test the actuator for ohm value .[/QUOTE]

 

@Peapvp I've been watching your stuff on YouTube -- excellent! Thanks for sharing with the world. I have a somewhat rudimentary knowledge of electronics, and very limited test equipment. (A nice VOM, a crappy VOM, an aging non-automotive oscilloscope, and that's about it.) I can't do the kind of diagnostics that you do, though I'm not afraid to open boxes and replace individual components (caps, resistors, transistors). Would you, as a general rule, at least recommend going through these various electronic units and at least replacing all the electrolytic/tantalum capacitors as a measure that might capture a large percentage of problems? Is there anything else you'd recommend someone in my shoes?

Thanks and have a great day!

Kim G
Mexico City, Mexico
Where there's not exactly a huge supply of good, used test equipment.

 

@CheckEngine Hi Kim,
Yes definitely. That’s a good starting point. I also would check all Diodes / Transistors and FET’s as well which can be done with a Multi Meter. I would also reheat all solder joints and add high quality 63/37 Solder with RMA Rosin Core Flux to each joint. The flux will clean out the connection off any accumulated moisture since these board substrates are Pertinax based and absorb moisture / humidity like a sponge once the Conformal Coating starts to break down and becomes porous after 25+ years. A new coat of conformal coating should be applied after a successful repair.
Sincerely Peter

 

Just managed to fix the cruise control on my 1988 560SEL. It gave me headaches for a while - surging and dropping out. So I did the what most recommend- replacing electrolytic caps and re-soldering the circuit board. Made no difference. Recently we had some flooding in our area and the roads are littered with potholes. I observed that driving over a pothole would bring in surging or dropping out of the cruise control. So I did some testing while driving and punching the dash/instrument cluster. And this would exactly generate these faults.

To cut a long story short, I took the instrument cluster out and removed the speedometer assembly. I found the cruise control (Tempomat) connector pin had a dry solder joint. Re-soldering the joint fixed the problem. I hope this helps.

 

Just managed to fix the cruise control on my 1988 560SEL. It gave me headaches for a while - surging and dropping out. So I did the what most recommend- replacing electrolytic caps and re-soldering the circuit board. Made no difference. Recently we had some flooding in our area and the roads are littered with potholes. I observed that driving over a pothole would bring in surging or dropping out of the cruise control. So I did some testing while driving and punching the dash/instrument cluster. And this would exactly generate these faults.

To cut a long story short, I took the instrument cluster out and removed the speedometer assembly. I found the cruise control (Tempomat) connector pin had a dry solder joint. Re-soldering the joint fixed the problem. I hope this helps. View attachment 2704400 View attachment 2704401 View attachment 2704402

Wow. Good job!