When switch is fully on no headlamps either side. When switch is halfway running light are on. When I pull back the turn lever for brights blue light shows on dash but no click or ability to stay in hi beam position. Is this a relay somewhere or ? Thx!

Not so likely the relay, but very likely the connector to it.

(Pics are from an '89, so you don't see the airbag's knee bolster, but the relay is located in the same place for '90. It got moved behind the center vents in '91.)







And if not, then the bulb failure warning switch.
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Art Benstein near Baltimore

There are two theories to arguing with women. Neither one works.

Art - thx for help here and past. My 1990 has the headlamp relay under the hood up by the battery next to the firewall. The relay has two separate 3 wire connectors attached. I got a used relay from the salvage yard but it didn't work. Could still be bad relay and I can swap for another. The IPD part numnber for this relay new is 112935 - Headlamp Step Relay 140 164 240 - 1307991 on ipdusa.com. I tried to check for voltage at the connectors and did find 12 volts on one pin when I put my positive lead there and negative to the battery ground. All other 5 pins showed no voltage that I could find.

My passenger side wiring/etc. down by the ECU looks a bit different than the pictures you posted. I did a lot of recent work under the hood to pull intake manifold and finally replace ECT with new Bosch as well as temp coolant sensor with new. That seemed to resolve old bad codes - see previous unending posts.

I could have affected something when working recently on ECT and frankly, hate to admit, I might have tried to charge the battery with charger connected backwards. Not sure if that would just drain it or fry something. So it's possible I did something there but not sure. However car is running fine but I do smell what seems like a rich exhaust which I didn't have prior to replacing ECT. That's my story. Any help is appreciated. thanks again. Mark

p.s. I took pictures of wiring by ECU but couldn't find a way to upload.

Hi Mark,

Your step relay is on the fender under the hood. That's for high/low beam switching. Your headlight relay is under your feet as I illustrated. Your symptoms point to the one under your feet, or if not, the red can bulb failure warning sensor just under the dash. I know the '90.


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Art Benstein near Baltimore

Experience is something you don't get until just after you need it.

Art - I did find the correct relay. Connector looks fine. There is voltage to the connector. I pulled and inspected and reinstalled w/no change. Not sure if there is a way to test the relay? If not I can get one from the salvage yard and try it.

Also can you elaborate on where the red can bulb failure warning sensor is, what it looks like, and whether it could be tested or would just need to be replaced if relay doesn't do the trick.

Thx very much again. Mark

Hi Mark,

The wiring diagram should help you test the headlight relay, which again I point out, is not a common failure item. The way to test it, is to use a test light or multimeter in voltage mode, to follow the power from the source (battery) to the load (headlights) by checking each place in the flow where it is accessible to a probe while the lights are switched on. Sweat the details before swapping parts and be aware that reliable headlight relay is not a common relay easily found just because it looks like one.

That's the way to prove the bulb failure sensor trouble as well. It is located above your knees inside the very bottom dash support rail. You'd need to remove the knee bolster to reach it.

Check volvowiringdiagrams.com for the lighting circuit. Although the diagram listed for the 1990 is accurate, it is hard to follow. I recommend using the TP31054-1 1987 wiring diagram manual from Volvo, which matches what you have in the '90, and shows clearly the path of the power to the lights on page 20 and 21. If you have any questions, fire back.

Again, this picture is from the 89 which doesn't have the airbag-equipped knee bolster your has. Remove it using a 30 Torx.


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Art Benstein near Baltimore

Optimist - half full, Pessimist - half empty, Engineer - The capacity is twice what it needs to be.

Thank you much Art. I will check it out. Mark

One more hint, Mark, when you go to measure connections, be gentle and try not to disturb anything much as you make contact with your probe.

Keep some way to know immediately if the lights come on, like a mirror or a helper, because the nature of all electrical trouble is in either connections that aren't connecting, i.e. a bit of corrosion, or connections that shouldn't be connecting, like a short circuit.

Your trouble is the former, so don't be too surprised if you get the lights to come on while you're trying to find the culprit, by knowing exactly what you just bumped or touched when it happens.
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Art Benstein near Baltimore

Raising teenagers is like nailing Jell-O to a tree.

Art - second post tonight replying to your post. Dangest thing. I took it out for another test drive after putting vacuum hose back on and the engine almost died, like bottom dropped out, after I came off the freeway and stopped at stop sign. So while headlamps work I still have aproblems. Got home and check engine light had come on. Read codes - pin 2 - 232 and 113, pin 6 224 (ECT again!). I definitely have smelled it running rich since I worked on it but worse now. Yipes. I will probably start another thread or take this horse out and shoot it. Don't know if you have any other advice here. Thanks for all the help. Mark

Art - great advice and thank you. I went down and swapped my step relay for the headlamp relay you pointed out and lights came back. Thank you for pointing me correctly.

However, after all the work on previous stall/dying problem I thought I fixed after replacing ECT/wiring, etc., car lost power briefly seeming to bog down while accelerating 3 times on the freeway at around 60mph and then came back.

Not sure if this was same as previous stall/die problem or something new and was ready to sell the car to the salvage yard. I'd been driving the car breifly for about a week after repairing but not much on freeway.

Came home and looked under hood to see if I'd left any hoses off when pulling intake manifold to replace ECT. Found the vacuum hose to what appears to be a diaphragm on the EGR tubing was off. Replaced that and hoping all is well and wonder if that could have caused the bogging. Anyway thanks again and I will mark this resolved.

Remember - just because you're paranoid doesn't mean they are not out to get you.

Very Best Regards - Mark in San Diego

Thx Art. I was looking on the wrong side. I will check there in the morning.