Hi. Never posted on a forum before, but I read them all the time. Car history. I have a 92 245. I have had Electrical gremlins for the 2 years I have owned the car. When I bought it there was a nickel that had rolled down from the dash and fused itself to the top fuse and completely melted every wire connected to that system. So my whole interior wiring harness has spots melted in it. With a good deal of tinkering and patching, i've got most everything operating.
Past few months my car has been having some shaky starts from time to time (like the motor rumbles and shakes violently sometimes as it fires up). And my car has been cutting out on me while driving. It happens most while flooring it, or when I go over harsh bumps in the road. Its not a so much of a sputter out, but more of an abrupt compete loss of ignition, and only for a split second. My first thought was some interior electrical because of my problem melted areas. But the only wire running in the damaged cluster was to the fuel pump. I tried disconnecting the fuel pump while idling, and the way it sputtered out was definitely not the same issue.
I went under the hood and went around wiggling and slapping wires and connections with the engine running and found a wire that when wiggled, cause the car to die. I repeated the test a few times with the same result, I traced it out and found it to be the crank position sensor. I wiggled it around pretty good and checked the connection. Then I couldn't get my car to start at all. I pulled the cps it looks fine. I put a new one and it still wont start. Any thoughts? I hope its not the brand new sensor is completely bad as well. Im thinking maybe the wiring running to the sensor may be bad? help! dead in the water here

 

Have you checked codes yet? if any.

that wire your talking about sounds about the right place to check...

 

I've been checking the codes. Nothing to report. I tried unplugging it and cranking it over and checking for codes. I'm not sure if a faulty CPS will throw a code. I exposed the wiring harness running towards the firewall and trased the sensor wire back a ways. It looks like its in decent condition. I'm curious where it runs so i can check it for continuity. I'm stumped. I'm wondering if miraculously something else failed at the moment i was wiggling the CPS wire? Could it have tripped some relay? Does something need to be reset? Could i have wiggled something else in the area?

 

Damn. I just got called to go work offshore. I have to put this off for a month now. I will have internet offshore and will be able to continue the dialog but wont be able do touch my car. If anyone gets any bright ideas tonight I might give it a shot. It frustrating because this car has always had a million problems but never quit on me like this.

 

This is what I got for Engine stumbles on Acceleration:

1: bad spark plugs
2: fuel injection system malfunction
3: clogged fuel filter
4: Intake manifold air leak....

CHECK THE CRANK PULLEY O-RING...IF IT IS CRACKED OR MISSING OR WHATEVER ELSE...THIS MIGHT BE CAUSING TIMING PROBLEMS......
AND WIRES THAT ARE LOOSE AND SHUT OFF FUEL/SPARK DELIVERY WHEN GOING OVER BUMPS ETC...

 

yeah, sounds like harness problems to me. hate to say it, but this might be a write-off unless you're willing to replace all the primary harnesses... dashboard, injection, ignition. if volvo still has them, they are probably a couple $100 each, otherwise, its junkyard cars, and you'd probably best be sure you get 1992 harnesses as there are subtle engineering changes in most every year.

you said the short was on fuse 1? thats just some fairly auxillary stuff, its powered by the "X" terminal of the ignition switch (on in I and II), and has the cigar lighter, tailgate wiper/washer (for a wagon only), power mirrors (if you got them), radio, and power antenna. hard to see that blowing up much other than maybe the ignition swithc itself and/or the yellow wire between the switch and the fuse panel.

the main power into the ignition switch is on a 4mm red wire from the positive terminal under the hood... the skinnier yellow wire after the switch would have fried long before a 4mm got warm.

the CPS is wired directly to the ICU, which on a LH2.4 240 is behind the glovebox.

re: harnesses... looks like for a 1992 240 wagon, american spec (B230F engine, AW70 automatic), the main engine-dashboard harness is part 9139204, this goes to the back of the dash, the fuse panel,and the relay brackets on either side of the engine compartment, and the left headlight and the horns.... the main engine harness which includes most of the engine sensors, ICU, ECU, and I dunno what all else is PN 3544669 for Cal and US Federated LH2.4 cars, with a manual or automatic gearbox. if you have LH 3.1, its different.


edit: oops, the engine harness, the 2nd one I listed, is NLA. the first one is $800-something new from the mothership, yeouch

 

Ive got the 5 speed with the LH3.1. I dont know, I cut into the harness to trace out the CPS and look for bad spots. it did have one tiny worn spot near the end where it was rubbing a little. But when I cut into the harness, everything looks cherry. Do you know what contacts or pins the cps runs to so i can check continuity? As far as the short, I agree it didn't seem to hit anything major, just a pain because the wire going back to the rear wiper melted itself to the wiring for all my blinkers and lights. I got most of that sorted. I'm just stumped on this no spark issue. Cant get my timing light to blink on any plug wires or the wire from the coil to the distributor. That would work right? Clip my timing light to the coil wire and it should blink rapidly?
Analogies, which is the crank pulley o-ring?

 

Should I be suspicious that my sensor came out and went back in so easy? It was hard to get at but game out loosely and went in loosely. I am suspicious because people are talking about breaking the bracket, my bracket seems like solid metal. Is there some brittle piece that is gone that would put my CPS in the exact location it needs to be?

 

from the 1992 240 greenbook:
CPS pin 1 -> blue-yellow wire -> ICU pin 10
CPS pin 2 -> red-yellow wire -> ICU pin 23
CPS pin 3 -> black (gnd/shield) -> ICU pin 11

(this is the ez116k, used with both lh2.4 and lh3.1 fuel injection)

 

I got it. I tested for continuity and the blue-yellow was not passing current. I took an educated guess and cut a tiny razorblade slit in the wire 8 inches back and got continuity to the ICU! I ended up cutting a 4-5" section and crimping a patch in there. Crazy, the wire looks fine externally. I had to unravel the shielding and then electrical tape it all back together. It doesn't look pretty, but my car is driving like a champ with no cutting out. So happy. Thank you pierce. I found so many posts about you mentioning that crank sensor, it really gave me the confidence to dive in when I notice you pointing out to people that its the wire leading back to the ICU sometimes. Thank you!