Hi,

My '91 740 has been having some stalling issues lately. Usually after the car has warmed up and while idling at stop lights or in heavy traffic. It also is harder to start in warm weather (2 or 3 attempts vs. 1).

I decided that before I bring it in I'd see what the diag codes can tell me. I have a 230BF and it looks like I've got the "Rex-1" ECM as it has the blocky coil rather than a cylindrical coil.

If I put the selector in position 6, I get a 1-1-1, which indicates all is well there. If I put the selector in position 2, I get three fault codes. The problem is, these don't quite match up with the guide on this site (ie: 2 and 6 are swapped). Using my (crappy) Chilton's book this is what I get:

2-2-3 - "Idling control valve signal absent or faulty"
2-3-3 - "Adaptive Idling control out of limits"
1-3-2 - "Battery voltage too high or too low"

The first two seem relevant; the car dies at idle sometimes. The third I'm not sure of. Perhaps I should clear the NVRAM and see if that fault code comes back. It seems like it would be normal to have at least one low or high battery reading since the last time the unit was reset. Checking the voltage without the car running gives me 12.5V. While running at about 1200 RPM it reads 14.5V. That seems a touch high, my meter sucks and I had no way of giving it gas while checking the voltage.

Perhaps if it's running with the voltage too high that has something to do with my other problem:

http://www.brickboard.com/RWD/index.htm?id=541404

So do those codes seem correct?

And can anyone recommend a book better than the Chilton's? I'm finding it's quite often just wrong or will be missing info; for example it tells how to check the voltage regulator, but gives no hint as to where it can be found. Mos t of the pictures/diagrams tend to not apply to my car. It's just to broad. I had a Haynes for another car and found it similar... Any pointers to something affordable appreciated.

Thanks!

Sounds like to me you have a dead IAC valve, id just replace that and code 1 and 2 ( in listed order ) will go away, the battery issue thats very odd, i know of alot of volvo's that have 14.5 at high rpm's thats actually normall considering all the electrical componants that volvo put in there cars ive even seen some at 15, and the codes here on the site are alittle mixed up youll have to look at both sets of codes for the Fuel injection as i noticed one for the LH didnt have my code but the reg did and visa versa and i have the LH for sure, in fact i actually didnt even know that high voltage would thorw and error low voltage i can see but high never thought about it.

Just check the 700/900 FAQ, it's more useful than a chiltons manual! not to mention if you get the pages dirty you can do one of two things... 1) clean the monitor! =) or 2) print another copy

Cliff Scott
89 740 16v