I'd like to show you where I'm going with this...
August 12, 2012 6:03 AM   Subscribe

The turn signals on my 2003 Volvo S60 only work once the car is fully warm. In addition, they then often work on the outside of the car without lighting the indicators on the dash. I really dislike not being able to signal in traffic and need this fixed.

Naively, I thought this would be something easy to fix.So far, the turn signal stalk has been replaced, and the fuse checked. One interesting detail -- I insisted on having the fuse pulled and reseated, and the turn signals and dash indicators worked for a short time after. The battery has also been disconnected and reconnected (voodoo) in hopes that would reset the electronics.

The dealer is now saying that the failure is in the driver's information module (DIM), which is the entire dash unit and significant dollars. I don't know how to read a wiring diagram, but here's the PDF for my car. Can anyone tell me if the circuit for the signals passes through the DIM from this? It's not intuitive to me that a partial failure of the DIM would cause this, to say the least. (not that I distrust the dealer.... much). All of the other instruments in the DIM are working fine, and high beams and hazard lights are functioning as well.

I'm about to go to a third shop to try to get this fixed, and I'd really appreciate any insights.
posted by vers to Technology (4 answers total)
It does sound like it will be something expensive, to be honest. The most bizarre faults often are an earth that is corroded (where the wires are bolted to the chassis) or an internal dry joint in an electrical box that only makes a contact when it has warmed up and expanded.

I'd go through the car and find any place a wire touches the chassis and take it off, clean the connections and the contact area of the metal it touches with scotchbrite/emery cloth and make sure it was refastened securely. Inside and outside. It could be an earth near the fusebox or inside the car, and if you are even a little bit handy and are ok with crawling around a bit this is annoying and time consuming but easy to do.

I am assuming no other issues with the car? No weirdness or oddity or anything at all electrical that you had dismissed as related? If there is, you can use the wiring diagram to start with the earthing points that are common to those two systems.

Something that works only when it is warm sounds electronic to me, though. Especially if it is consistent - non-functional when cold, works when warm. It is perfectly possible that something that only works after time could be within an electrical box, and the delay on the dash to show the light seems to suggest it is at the very least affected by the same fault, although I can't say whether or not it is causing it.

If it is the DIM, though, and this is warmth dependent, then the DIM will get warm by virtue of just being on, rather then needing the engine running. If the fault works when cold, but you can leave the ignition on (you may need to leave a battery charger on it during this time to ensure voltage) and the fault will be consistent and disappear as usual, then that is a test you could do. Essentially you need to isolate whether it is heat from the engine (which would make me inclined to think earthing point issue) or electrical heat within the DIM or other part of the signal circuit (including the fuse box, relay box/flasher unit etc).

Sorry that is a bit rambling, but hopefully some of that helps.
posted by Brockles at 7:12 AM on August 12, 2012 [1 favorite]

Brockles, I'm really grateful for your expert input. There's no other bugginess with the car at present. One thing that's been tweaking me is when the car is warmed by ambient temps (90+ degree weather, black car sitting in the sun), the signals don't work; it's only when the engine warms up that they do, and that is consistent. Unfortunately, it also takes 12-15 minutes, which is just about exactly my commute to work.

I wish I were even a little bit handy but I'm not, so I'll pass your thoughts to the new mechanic with whom I hope to meet next week. Coincidentally, he had the same problem with his own S80, and seems to have a very solid problem-solving approach.

If it is the DIM, would you be hesitant to put in a re-manufactured one? I can get one pre-programmed to my car from Xemodex that would save me several hundred dollars. (Another aside: It's interesting that Xemodex offers a limited lifetime warranty; if I buy a brand new DIM from the Volvo dealer, the warranty is only two years.)

Again, thank you for taking the time to answer my question -- much appreciated.
posted by vers at 8:48 AM on August 12, 2012

when the car is warmed by ambient temps (90+ degree weather, black car sitting in the sun), the signals don't work; it's only when the engine warms up that they do

But in that example, there is likely not the same warmth inside the box from it being 'on' for a while. Just a thought. Points towards something in the engine bay (like an earth point) though to me. It's a weird one, though.

would you be hesitant to put in a re-manufactured one?

I'd be fine with that. If it is a manufacturer that gets good reviews and, for instance, gets no results on "(manufacturer) +scam" google hit...
posted by Brockles at 10:30 AM on August 12, 2012

Good point about the DIM temp. Hopefully, the next mechanic my car sees will take the time to really troubleshoot and check earth points. Wish I could do that myself, but better I don't try. The other shop and the dealer both reported to me that the signals were working; yep, they work when the car is warm, and I had to drive it to get here. Same issue I described when I made the appointments... I was quite clear.

Xemodex seems well regarded in several Volvo forums, and hey! they're Canadian, so I expect honest, polite and helpful :)

Other parts not ruled out yet that other Volvo owners have encountered:
Relay switch
Hazard switch
Central Electronic Module
Ignition switch


Brockles, thank you.
posted by vers at 3:14 PM on August 12, 2012

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