My daughter's 88 240 died the other day and I'm trying to troubleshoot. I've checked the fuel pump relay per the bentley manual, and the next step is to check the main relay. The diagram says it's located under the glove box with the FP relay, but there's nothing there. Anyone know?

 

I had an 87 wagon and certain relay locations indicated by my Volvo manuals did not corelate with my wagons actual location or my wagon simply did not have that other relay......
I had the fuel pump relay below the glove box behind the carpet...at the local junk yards I looked at other Volvo's that had the fuel pump relay along with a smaller cube relay....

you have the giant red switch under the steering column....

CHECK THE DRIVERS FOOT WELL, LEFT SIDE UNDER CARPET UNDER A METAL PLATE....

 

[/QUOTE]
CHECK THE DRIVERS FOOT WELL, LEFT SIDE UNDER CARPET UNDER A METAL PLATE....[/QUOTE]

Yep, there's a relay under there. I'll report back after I test.

Thanks!

 

OK, I was proceeding ahead with the Bentley tests, it has four steps that test various combinations of terminals 87/1, 87/2, 30, 86/1 and 86/2. Unfortunately, the relay is labeled 86, I, 31, S, 31b and 15.

Any idea what to do now? Incidentally, I was in the middle of the ECU test that calls for a "Fuel pump power supply from Main Relay" test, and that failed. So I might be on to something.

 

on 240s after about 83 or 84 and 740's/940's up to about 1994, there's a single relay module that has two relays inside, one half powers the main fuel injection circuits, the other half is the fuel pump. this combo fuel system relay is behind the glovebox on 240s, and in the main relay panel behind the ashtray on 740/940's. on the 240's, its on the same fuel injection harness that goes to the ECU (just forward of the passenger side lower door hinge) and through the firewall.

 

The bentley manual does not acknowledge this. So maybe this relay is bad. Is there a way to test it or should I open it up and look for solder cracks or just replace it on suspicion?

I also tried to start it with the fuel pump jumpered manually. It did not start. I shot some starting fluid in the intake and it does kick and try to start, but it feels like it's starved for fuel. I did test the pump flow, it's good, but I did not do a pressure test.

 

you can test it from the ECU connector with jumper wires and a volt meter. what year is this, again? LH2.2 and 2.4 are different. ah, 88 is LH2.2 (89+ non-turbo and 90+ turbos are LH2.4 unless they are something else like Regina).

I'm pretty sure I detailed the steps in a recent post but I'm just too tired to dig it out tonight.

 

ok. I'm a couple beers into the evening, but I think I can explain this LH2.2 diagram I'm looking at.

your ECU is just in front of the passenger side door hinge. remove the felt kick panel, and the side panel (which requires removing the door frame trim, and some clips that are under it).

at the ECU connector, shine a small bright light into it, and you should see the pin numbers.

carefully pry the plastic cover off the fuel pump relay. carefully plug it back in. if you gently press down the fuel pump switch on the relay when the ignition key is in II (on), you should hear the fuel pumps turn on.

if you use a piece of wire to connect pin 21 to ground (pin 25), the ECU half of the relay should switch on (see it click), and a volt meter should read power on pin 9 to ground. disconnect the jumper and there should be no voltage on pin 9....

if you see both those things, your fuel pump relay seems to be fine.

 

Thanks Pierce,

Got too many things scheduled today, I'll get back to it on Sunday and will let you know how it turns out.

 

I missed a test. turning the ignition switch on (II) and grounding pin 17 at the ECU connector should also turn on the fuel pump half of the relay which in turn should turn on the fuel pumps.

 

Pierce,

I did the tests you suggested. All is good.

Again, the engine will fire a bit if I hit it with a bit of starting fluid, but it seems it's not getting fuel. Is there a way to test if the injectors are firing? If they are not, is it a bad ECU or is there something else that could possibly be the problem?

 

ok, disconnect one of the injectors, turn the ignition on, and use a volt meter, one lead to ground, the other lead to each pin of the injector connector, one at a time. one of those pins should be +12V (the other should be close to 0), if thats the case, then the injectors are getting power.

to see if the injectors are actually firing, there's a gadget called a 'noid light' that has the same connector as the injectors, you plug the injector cable into the noid light, and crank the car, and it should go blink-blink-blink-blink. if it doesn't blink, the injector isnt' being fired. if the injector IS being fired, then its time to look at the fuel delivery again.

 

I read that you can use a test lamp instead of a noid light. I tried it, and get only one flash of the light right at the beginning when I crank the engine and then nothing. So it appears that the injectors are not firing. This makes sense, since the fuel pump puts out a very strong stream, and I've verified that the relays are working. I also ran the fuel pump directly from the battery, and I get no firing at all. With starting fluid, it does fire, but won't start. Could it be that the ECU is bad? Any other ideas on what to test?

Thanks!

 

do you see power on one side of the injector plug relative to chassis ground when the ignition is switched on? it doesn't matter which pin, just that one of the two pins is 'hot', while the other isn't (don't short them together)

if you DO see power, AND your test light only blinked one, I have to suspect there's an ECU or wiring problem.

 

Yes, I do see power when I switch on the ignition, but it's only for a second or two then it goes off.

My hall sensor connector is broken at the distributor. Is it possible that's the problem? I would imagine that it wouldn't spark if the hall sensor wiring was shorting out.

 

well, those hall sensor connectors can crack, and the signal can still get through. my kid's 240 is that way right now, I have the replacement part but haven't gotten around to fixing it as its not actually 'broken'.

wait, come to think of it, on a LH2.2 240, the injector power is the same as the fuel pump power... I'm too used to LH2.4, where it is powered same as the ECU which is on with the ignition, and not the fuel pumps which are on when there's timing pulses.

so, you'd need someone to crank the car to confirm the injector power comes back on while its turning over. again, this is between one injector connector pin and chassis ground, NOT between the two pins.

 

I just now tried it with the test lamp connected to ground. With the probe touching one of the connectors, I cranked the engine and the light came on then went out and stayed out while cranking. I then touched the probe to the other connector and got the same thing, which seems strage.

 

I found a wiring diagram on volvo-forums.com. Does the hall sensor interface to the ignition controller, and then the ignition controller reports to the main ECU? In other words, is it possible that the ignition system is firing but the pulses are not getting to the ECU? Is it possible that the test lamp lights when I start cranking, but then the ECU believes that it is NOT cranking, because it's either not getting the proper signal from the ignition controller, or it just isn't interpreting the signal correctly, so it then shuts down the fuel pump relay and injectors? From the diagram, it looks like the power to the injectors and the fuel pump is the same, it comes from pin 87/2 on the fuel pump relay. It now makes sense why I get the same result from either pin on the injector connector, because the grounds on all the injectors are all tied together.

 

yes, hall -> ICU via 3 wires, and ICU pin 8 (green wire) to ECU pin 1

the diagram you want to use if you can find it is Volvo 'green book' TP-31099/2, 240 1987-1988 Wiring Diagrams. US models have the 'Chrysler computerized ignition system'

there was a service bulletin on these chrysler ignition ssytems that had the shop do some enhancement to the connector, involving cleaning the pins in the socket on the ICU, and installing 'sleeves' on a set of the pins (3,5,9) which are the pins to the hall sensor, then filling the plug on the harness with dielectric grease and reinserting it. hmm, it says 1984+ got these sleeves from the factory.

my experience is, you can NOT rock that plug when you disconnect it, you have to pull it straight out and its a beotch. I used a little pointy tool (dental pick style) to gently press in on each of the pin sleeves in the 'plug' so they would be tighter when reinstalled, this solved an erratic stalling/nostart problem.

if you do remove the connector on the ICU, you might stick a wire into ICU pin 8 and run it back to the ECU, and use a ohmmeter to check continuity from that wire to ECU pin 1, verifying the wire is intact, also check resistance to ground from ECU pin 1 with the ICU unplugged (should be open circuit, infinite ohms)

 

YES!!! It started!!

Must have been a bad connection at the Ignition Control Unit. I unplugged and re-plugged the connector a few times to improve the contact on the pins and then packed it with dielectric grease.

It fired right up!

So, my conclusion is that pin 8 on the ICU was not making good contact. This is logical since I was getting spark, but since the injectors were not firing, the signal from the ICU to the ECU was not getting through.

Thank you Pierce the valuable information, and for helping me to understand the system and working through the troubleshooting. I was getting ready to go to the pick-a-part and procuring an ICU and ECU on suspicion.

Maybe this thread will help keep someone else from either blowing their brains out or torching their beloved brick!

Thanks again!