Trying to help my son troubleshoot an intermittent no start problem. The last few times, I have gotten a call for help I was able to confirm that it was cranking fine. When I got home, we were going to start the diagnostic process (park, fuel, etc) but it started just fine. The next day same thing. By the time I got to look at it, it started fine.

Does the fact that it is intermittent give a clue? Usually this just makes the troubleshooting process more difficult but I thought I would ask.

ON another note, on the 740 how do you actually get at the distributor. I took a quick look, and could figure out how to get the cap offf as it butts right up against the firewall.

 

First look at the ICU harness connector. The metal sleeves have little tiny prongs in them that need to be bent back in to contact with the male ends at the ICU. Next time your son encounters this no start tell him to jiggle that part of the harness. before trying to start again.

Be very gentle with the prongs, so you don't bend them in too far that they smush down into the sleeve when you reinsert the plug. or it's a PIA, and you'll need a pair of optivisors to get it back in place.


After that, when you know that connection to the ICU is good, if it's still happening, it's more than likely a grounding issue.


Also a test you can do is remove the impulse sender connection and jump pins B & C.


You should get spark at that point. If you have an inline spark checker, place it at the coil to see it.

Be very gentle replacing the connection and start car. The plastic for that connection on the distributor side, can become super brittle so use ultimate care when removing and reinserting that plug.

That plug is shielding 3 tiny wires that you do not want to deal with.



There's also a possibility of it being the AMM, but try the stuff above first as I'm testing a theory that I found the ultimate answer for certain kinds of no starts.

 

When troubleshooting no-start issues, always start with the easy stuff. Your symptoms sounds to me like a radio suppression relay (or fuel injector relay) going bad. Its a black relay that sits on one of the strut towers. Pull it out, re-flow the solder, and see if that changes anything.

 

Finally had time to look at it toay. Unfortuantely It is starting just fine now. I will try out the various option mentioned. I will make sure to post back from I find.

Ian

 

those ICU pin/sleeve instructions sound like the ICU used on a LH2.2 240 with the chrysler ignition controller. I don't /think/ a LH2.2 740 turbo uses this same ICU but I dont have the docs on those, my 740T is a 1992 w/ LH2.4.

 

My 740 is a non-turbo 4 cylinder. I have teh Haynes guide but it it sometimes doesn't include the stesp for the 740.
I did find what I thik is the ICU attached above the gas pedal. It does look to be very securily attached.

 

Although the no start has happened several times over the last few weeks, today was the first time I got get to the car to do a little diagnostic work. Unfortunately I didn't have my tools with me. Plenty of spark everywhere. Some one mentioned the fuel injector relay. I will take a look at that tomorrow. As for the ignition control module, it is up under the dash and is very well anchored. Not to sya the problem isn't there but it is not likely due to a lose connection. I have a Haynes manual but it really doesn't cover the 1988 740GL 4 cylinder very well. Is there a online version somewhere that is better?

 

Thats the last year Bosch LH2.2 fuel injection. 1989+ are LH2.4, same as most 940's.



The best documentation are the Volvo service manuals, known as greenbooks. sadly, they are no longer available from Volvo as books. DVD's are available from the Volvo Club of America (VCOA) with copy protected PDF's of most of the greenbooks, but thes aren't complete, nor are all of the scans that great. I have these DVDs for 240s and 940s, which covers my 1992 740, but not the one for the 7xx at large.

 

oh yeah. tons of useful help here on your car.
Volvo Maintenance Hints for 700 900 S90 V90 Models

 

So got out to his 740 this morning with a small collection of tools. Unfortunately the car just started without a problem. Since it isn't spark I am working on the premise of the it is related to fuel. Some one had mentioned the fuel injection relay. I looked for it this morning and can see them behind the fuse tray but could figure out how to get the dash open enough to work with the relays.
Ian

 

after removing the ashtray, remove the plastic bezel around the cigar lighter socket (it just unsnaps) and there's 1-2 screws behind it, remove those, and the tray and cigar lighter come out, then you have better access to the relays.

 

tonight it refused to start again. It was pitch black out so I reached in and reseated all of the relays by pushing in all of them. I couldn't take them out since I had not read your earlier email on removing the bezel around the lighter. LO and behold, the Volvo started. Not proof but hell of a coincidence.

Does that point to the fuel injector relay? If so, is it the problem most likely related to the relay itself or the socket the rely plugs into?

 

i've never had any problems with a relay socket unless it was badly corroded, which shouldn't happen unless the interior of your car has been getting all damp and wet due to rain leaks or whatever.

its possible the relay was just loose, but its also possible the relay is going bad. they often can be taken apart and resoldered, this can fix one common failure mode. if you do get a new relay be sure to get a Stibel or Volvo one, thats the 'real thing', the other off brand ones are much less reliable.