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Can 82 380sl ICU

1K views 2 replies 3 participants last post by  joe1973 
#1 ·
Be subbed out to the 83-85 units ?

I know it will fit, turns out the PO installed the later version, the two extra pins are outside of the connector base.

Chasing a fast idle...maybe it's just in closed loop ?
 
#2 · (Edited)
Maybe, with a little rewiring.

I compared 82 and 84. The 84 has these additional inputs:

- 8 Cold start valve energized
- 9 AC compressor engaged

I think both of these would raise the idle a bit, so you can probably not worry about them. The 82 seems to do OK without these inputs

The difference is on pin 6. The 82 sees 12V until the coolant temp switch opens, then it gets 0 V. The 84 wants a ground from the oil temp switch until it opens at 50 degrees C. This signal is what tells the lambda computer to go into closed loop

I can see how the Pin 6 difference would confuse the 84 and make it not work, or maybe fry it completely.
 
#3 ·
Check my post on the "ghetto solution". Essentially check your idle valve. Easy to remove in 1 min thugh you also need to remove air box. Test valve by applying 9v battery to prongs and you can see down one end the movement of internal mechanism. Dont run for more than a 5 secs as ive seen on other posts. If it looks to move fine, check power to your valve unit. Passenger footwell fuses. #6 in my 85 380 sl. If all else fails, maybe you can be the second on this board to try the ghetto remedy. It shuld be temporary but at least i know issue is my valve unit and not ICU.

The fast idle problem is really annoying and you almost feel you're shortening engine and trans life in our old cars. Good luck.
 
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