SRS Light Stays on ... related to Short of Alternator ??

[Wiley]

We have an electrical short in the dash of our '93 Volvo 940 wagon that frequently results in only the "SRS" and 'Seat Belt" lights being illuminated once the key is turned. When this happens, the "SRS" light stays illuminated after starting. This apparently shorts the alternator, causing the battery to loose charge after 20 minutes of driving. Of course, once this happen the engine fails.

This problem happens intermittently. Many times all the normal dash lights (oil pressure, heat sensors, etc.) come on and go off as normal following starting and the car runs great.

When the "SRS (light) Happens", we have to resort to PERCUSSIVE INTERVENTION. That is the light can be made to go off by a few well-placed, strong pounds on the dashboard. (You really have to hit the dash quite hard to cause the light to go out.) Once the light goes out, the car runs great.

Also, FWIW ... in the midst all this pounding on the dashboard ... our gas gauge no longer works.

We've had a couple of mechanics take our dash apart and re-seat all the connections to the instrument cluster ... this seems to help for a day or two, but the problem persists. They've suggested getting a new/replacement instrument cluster.

Is a new instrument cluster the answer?

[bangmo]

Sure would of been nice for someone to respond to this question. I,m having the same exact problem.

[rogerthechorister]

I'd sort of expect a short across the alternator would result in a MAJOR electrical fire in very short order.

The application of percussive persuasion is usually only of assistance to a stuck relay or an open circuit, but I'd sort of expect something related to the starter relay to remove battery voltage from quite a number of but not all circuits (the radio for example always goes off during cranking, but ignition and fuel pumps would HAVE to stay on).

Strange though it may seem that suggests to me that there may be an ignition lock issue.

Most Volvo instrument panel faults are related to the connections of the panel to the loom, IMHO.

All very general, but maybe one of the cognoscenti will get onto the case now!

[Steve940estate]

I think the seat belt warning is in some way connected to the indicators. I disconnected the plug under the front of the seat each side to stop the noise as I got fed up listening to it any time I started the car up.

Not sure about the SRS light but it sounds like somethign is trying to earth itself through it.

When my instruments were playng up I found that there was a bad earth where the individual instrument components attach to their own PCB. Each of the gauges is mounted on one of these boards and it's the screws that mount the cast alloy frames to the board that seem to come loose. I tightened these screws, refitted the gauge back onto the main external flexible board and so far they have been OK since.

[jor]

A replacement instrument panel is required.
For some reason the alternator must be supplied with voltage via the panel for it to function (if the alternator isn't charging the battery warning light should come on).
You may find more information in one of the electrical system green books.

jor

[jor]

PS: Try this search 'alternator exciter circuit'

jor

[Dr. Rog]

Originally Posted by jor

A replacement instrument panel is required.
For some reason the alternator must be supplied with voltage via the panel for it to function (if the alternator isn't charging the battery warning light should come on).
You may find more information in one of the electrical system green books.

jor

A most imaginative interpretation as stated, but I am sure there is truth in there.

Firstly I am persuaded by the chaps above that the instrument panel is defective. Probably a simple connection or dry joint, otherwise percussion would not work. I strongly suggest stripping it down and checking/re-soldering all the faults in the FAQ. If only to preserve your millage. If you can get another give it a go.

There could be a fault in the alternator regulator or monitoring circuit. Rather than "supply" to the alternator it could be the short is from the alternator through the panel, via the lead to the charge warning light. If that short makes the alternator regulator cease to allow current to the battery you will not be charging.

Certainly a perplexing problem.

[maxPower]

This is exactly what is happening to me.
Car came with paperwork denoting alternator issues. Looks like the exciter was spliced into the red/green coming out of the radio suppression relay (good?).

Intermittent no start / random stalling. Very near and far apart. Good for 3, 4, 6 months a year - then sudden a week of downtime.

Just happened again a week ago and I resolved it (after being towed home) but striking the dash to get rid of the SRS light, as was prescribed by the previous owner, and then the car started.

So I'm wondering if there is a correlation happening behind the dash. I've not gotten into the electronics back there except to swap ignition switches before so I'm trying to gather as much information before I dive in.

Did any of you figure out what specifically failed in your 'strike the dashboard to remove SRS warning light' dilemma?

I also notice my dash lights change - a few days ago was getting only SRS and Seat belt lights when ignition was in second stage, but today was getting check engine, oil, seatbelt. So this is another clue...

[maxPower]

Originally Posted by Dr. Rog

I strongly suggest stripping it down and checking/re-soldering all the faults in the FAQ.

What section of the FAQ is this in reference to?

Originally Posted by Dr. Rog

Certainly a perplexing problem.

Indeed

[maxPower]

Can't edit my previous message, but I did find this in the FAQ:
https://www.volvoclub.org.uk/faq/Ele...anelRepair.htm

warning lamps that do not light up when the car is started or the key is in position II and SRS light that stays on without throwing any codes.

Looks like I'll be removing the cluster and inspecting for damage.