ICU Location? - '90 560SEL
 

Good evening -

Need another 560SEL owner or tech to point me to its location. I've borrowed a working ICU from my Indy but he was thinking it was passenger foot sidewall (Nope - sorry - no fuse panel there) or fuse box (Nope - try again).

Thread search suggests under the carpet in the passenger floorboard or up behind the glove box; another post pointed to under the dash, drivers side.

Do I have another '90 560SEL owner here that can tell me for certain before wrenching my back or messing with the carpet, etc.?

Wouldn't have 4 MBs if it weren't for this forum ( my wife thanks you for the infection )!

Kevin

P.S. - forgot to mention, if it makes a diff, its CA spec

The ICU is located behind the right kick panel in the passenger compartment, but you never posted the problem. Perhaps it has nothing to do with the ICU.

Peter

The problem...
 

...is I own 4 older MBs (LOL)!

I'm having an erratic and somewhat higher than normal idle problem - usually 950 - 1050 rpm, sometimes normal around 650- 700. It also fluctuates while sitting just enough to hear the RPMs changing without registering on the tach (above numbers are while idling in Park).

ICV seems to be functioning so I thought a quick swap with a known good ICU would either identify or eliminate a possible cause.

You say "behind the kick panel" - do you mean passenger side footwell wall?

Regards,
Kevin

Yes passenger side, but I don't think it will solve your problem.

Peter

What is your thinking?..
 

... and please (!) don't say the ECU is involved (way $$$).

Its not a traumatic problem now, but sooner or later the tranny will rebel, not to mention other unmentionables.

Do you have some pointers?

Regards,
Kevin

You most likely need to eliminate vacuum leaks. This link for the 6 cyl engine is similar in principle.

http://www.peachparts.com/Wikka/M103VacuumLeak

Kevin,

Warren has a good thought with the vacuum leaks that bears checking, but I kinda think a vacuum leak would be constant. I have seen slight binding in throttle linkage do this. You need to remove every piece and lube includind the pivot points. If that doesn't do it, there still could be an erratic problem in the idle control circuit.

Peter

I had an ICU go out. It is the silver box attached to the coil, right? Mine and the one I borrowed to test (from a 500 SEL) were in the driver’s front fender well and held on by 3 screws. The one under the passenger foot well is the LAMBDA control, isn’t it? Also replaced the idle speed control module, which is behind the glove box. Your surge in idle could be a number of things. Vacuum, Idle speed control module, air slide valve, ICU… Good luck!