99 S80: Major electrical failure. Please help?

robyr · Post by **robyr** » 12 Dec 2010, 12:46

am having some major electrical issues on my S80. I recently purchased the vehicle, and all systems were functioning perfectly, up until about 12 hours after buying it.

Coming home from a trip, my lights (low beams and corner lens), cabin climate control, radio, windows, sun roof, passenger power seat, reverse lights, and most non-engine systems all suddenly stopped working. I had just adjusted the sunroof and we heard a click, then all listed systems failed. The sunroof was operational up until I stopped the car to diagnose. After attempting to diagnose the issues, we noticed that sun roof had now failed, and the gear shifter would not allow us to select a gear (would not move out of park.). We are able to select a gear, so long as the car is not actually started.

We have tested most fuses that we could find (I.e. Cabin fusebox, trunk fusebox, and engine bay relays/fuses.). All fuses are fine, which led us to the CEM for diagnosis. The shunt that causes many people grief looks fine, no charring or oxidation. In fact, all connections and wires seem to be intact and clean. Extremely clean compared to my 87 300zx which was forever plagued with electrical issues.

Highbeams, drivers seat, and interior cabin lighting (minus the dash accessories backlighting), and dashboard instruments all work, along with the parking lamps, so long as the headlamp selector switch is not switched to "headlamps on".

We are at a loss of what else to check, not to mention that information has been scarce. We have also tried the key reset, as well as the battery terminal reset, none of these have effected the symptoms listed. We were able to get one low beam light to shine when we removed the low beam relay from the cem, but only when I used the high beam stalk switch.

Any information or hints would be much appreciated. I bought this vehicle specifically because I was tired of working on my z, and now I am knee deep in a nightmare 1000x worse than any issue my z ever threw at me. The car is now undrivable, due to no lights or wipers nor being able to select a gear, so I am dead in the water.

Post by **JDS60R** » 12 Dec 2010, 13:26

Sounds like a distribution issue.
I would start with the ignition switch and test its outputs when on.

Above, in the drop down for "Repair Database" you will find the wiring diagram for your car. Feel free to download it for free.

I don't want to sound overly optimistic but I prefer major failures like this. Pick any of the systems that failed and trace from the battery to the unit itself for voltage. In colder weather many have had a battery cell fail intermittently so if you have a battery you can attach with jumper cables to your current one you can begin to rule out the battery failing under load.

If the battery passes ( I hope it doesn't so you can have a quick fix) then just follow the circuit to the fuse and then the ignition switch and then the units themselves. Massive shorts that wreck multiple components are extremely rare in these cars.

I am guessing that click you heard might have been a major fuse blowing or an arc in the ignition switch.
I guess you will want to know how to take that out. I'll post the directions for you.

Post by **JDS60R** » 12 Dec 2010, 13:29

Ignition switch removal

Remember to stay away from any airbag wiring

robyr · Post by **robyr** » 12 Dec 2010, 13:35

WOW! Thank you so much for the quick reply.

Yes, we also suspect a power distribution failure. For what it is worth, I have tested with a known good battery out of my fathers Frontier, no change in symptoms. My next tests will focus on tracing a single failed component, probably the head lights at first. I have also heard about the ignition switches in these vehicles being a particular burden for this type of failure.

This site has been a tremendous help already due to the wiring diagrams that we got! Where are the major fuses located? As an aside as well, would this sort of failure cause the issue with the parking lamps cutting out when the headlamp selector is activated? Sorry for the serious newbieness, but I have been a Nissan guy for half a decade, and Ford before that. I'll say this much, when you have an electrical issue on a Z, it is generally a fatal failure, taking the harness out most of the time. This is the main reason I have been in panic mode. I began to wonder if I just sold my baby for nothing, spending 3k on a car that is non functional, but you have allayed these concerns.

Post by **JDS60R** » 12 Dec 2010, 13:46

Fuseboxes - Most modern Volvo's like yours have 3
1 under the hood
1 under the dash
1in the trunk

On the first page of your downloaded wiring diagram you will have EZ links to them under "Fuses"

""""would this sort of failure cause the issue with the parking lamps cutting out when the headlamp selector is activated? """"
Sure - electrical failures, arcing etc can cause lots of odd symptoms.

Don't worry about this being an electrical nightmare. Volvo's are the Lego's of cars. Just trace it and replace it. ( This is a compliment to the Volvo engineers showing they understand what it actually takes to work on a car)

Your model and year have some ETM and transmission issues so maintain them well and be knowledgeable about how to handle it if the problem will arise. A well maintained Volvo will serve you well. A neglected one gets sad and has been known to start a relationship with tow trucks. Use of high quality synthetic fluids has proven its value with these high powered turbocharged cars.

robyr · Post by **robyr** » 12 Dec 2010, 16:37

Well, we have checked the main engine bay fuses, verified 12+ on each fuse, and we have verified 12+ to the cem wires going to the overload relays, so that checks out. There is also 12+ at the cem relay for low beams. We do not have 12v at the headlight harness connector for the low beams, but we do get a reading on high beams. Low bema relay never clicks when activated. Any ideas?

Post by **JDS60R** » 12 Dec 2010, 17:25

Check the relay for lack of trigger signal, or lack of voltage input.
Keep working your way backwards

Did you check the ignition switch outputs yet???????

robyr · Post by **robyr** » 12 Dec 2010, 17:36

Oh yeah, we checked the ignition switch too, it's seemed to be working fine though. It is melted slightly on the plastic parts though, is there something specific to look for? The pins meter out, from what we can see.

Post by **JDS60R** » 12 Dec 2010, 17:43

If its melted at all - replace it

What about the low beam relay??
Do you have supply voltage??
Do you get a trigger signal???

Post by **JDS60R** » 12 Dec 2010, 17:49

You must also inspect the systems on the line that the ignition switch connector was charred. Resolve any dead shorts before installing the new switch. Most common failures/shorts are high load components like lights and blower motors .