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 SAAB 96 electrical woes.
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 24 Sep 2021 :  19:33:20 Show Profile Reply with Quote
I'm currently helping another SAABist in Fife with his 96.

We fitted a new water pump today, to solve an overheating problem, but this is not why I'm posting.

The car has some strange electrical problems, that I thought some of the V4 Gurus can perhaps throw some light on.

When you switch the ignition on we have the following:-

No ignition light
No oil light.
No fuel gauge
When the engine warms up, no temperature gauge
No indicators.
No Hi beam, no click from the lighting relay, no indication in the speedo dial, and the main beams don't come on. Dip beam and side lights work.

The oil pressure switch and temperature sensor are connected.

Now I suspect the issues with the right hand dial containing the various warnings lights and gauges, are maybe unrelated to the indicators and hi beam, though maybe not.

I have checked and there is 12 volts at the top of the fuse box, both "always live", and "ignition switched live" fuses.

I have removed the right hand dial, and unplugged the connection on the back.
There is 12 volts coming from the voltage regulator to pin 5, and the earth on pin 12 is good.

We have tried not one, but TWO other Temperature/fuel gauge dials, and still nothing.

It used to all work, when I was there last year helping with other issues. (prior to the pandemic)

The car starts and runs.

Any ideas?

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 24 Sep 2021 21:43:25

green96v4
V4 Mad

Canada
621 Posts

Posted - 25 Sep 2021 :  11:53:07 Show Profile Reply with Quote
what's the earth that fixes under the dash like? (on the metal bar that holds up the steering column)

On my wiring diagram they come out of pin 12 and piggy back over the the speedo and then earth under the fan/light switch but as they're both connected to the same earth, (and both acting up) I'd chase that
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 25 Sep 2021 :  12:01:53 Show Profile Reply with Quote
Hi Matt, hope all's well across there in CDN.

Checking the earth from the black wire in the socket, that goes to pin 12, directly to the battery terminal, it seems to be good.
I know it has to be something simple, that is affecting so many functions. A bad earth was the 1st thing I checked.
As I said in the original post, there is 12volts at pin 5 on the plug, as you'd expect.......ie there's power and earth to the gauge assembly.
It's very strange.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 25 Sep 2021 13:09:30
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green96v4
V4 Mad

Canada
621 Posts

Posted - 25 Sep 2021 :  16:05:38 Show Profile Reply with Quote
I did have the strangest thing going on with my car where the charge light was on even with the key removed and then went out when I turned the ignition on (ie, when you'd expect it to light up) which turned out to be the ignition switch, replaced that and it fixed the problem (I've read other forum solutions that spray them with electrical cleaner until gunk stops running out of them....)

only other things I'd be checking are the voltage regulator and the Headlight Relay (and then obvious things like fuses and the multi pin connectors - Autosparks re did my loom but mixed up 2 blue wires in one of those multi-pins under the dash and it gave me the run around for weeks with odd lighting and strange things happening - "Electrickery" can be a bugger for doing it's own thing!

All good over here in Canada, enjoying the Autumn (Fall) colours - beautiful time of year and took my car for a 120km cruise to a friend's cottage last week - A. Pretty. Good. Day!
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 26 Sep 2021 :  19:28:20 Show Profile Reply with Quote
Matt
Aye it's something to do with Supply or Earth I'm sure.
Interesting to see you saying that you drove 120 km to a friends cottage.
Boris and his band of Tory loonies are apparently considering switching the UK back to the Imperial measurement system.......

What he doesn't seem to realise is that apart from the US, almost the whole word uses the metric system.

I spent almost all my working life overseas, worked on every continent except Antartica, and more countries than I could list, and in only two, did I see MPH on the speedo of the cars. The US, and one Caribbean island I've forgotten the name of!!!!


1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 26 Sep 2021 20:17:08
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Derek
V4 Guru

United Kingdom
2050 Posts

Posted - 27 Sep 2021 :  11:19:29 Show Profile Reply with Quote
Isn't there an earth connection behind the fuse box that can go funky? Remove and check.
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green96v4
V4 Mad

Canada
621 Posts

Posted - 27 Sep 2021 :  12:55:35 Show Profile Reply with Quote
quote:
Originally posted by andydeans3
Matt
Interesting to see you saying that you drove 120 km to a friends cottage.
Boris and his band of Tory loonies are apparently considering switching the UK back to the Imperial measurement system.......

What he doesn't seem to realise is that apart from the US, almost the whole word uses the metric system.

I spent almost all my working life overseas, worked on every continent except Antartica, and more countries than I could list, and in only two, did I see MPH on the speedo of the cars. The US, and one Caribbean island I've forgotten the name of!!!!



Yes I guess I've been here too long and now think in kms (even though my speedo is still in Boris's mph) and as for the US, they just do their own thing, even their gallon is different to an imperial gallon (probably to fool them into thinking they're getting better value for money!)

One last thought on the electrical woes, there's also an earth on the inner wing (down under the voltage reg.) could it be that one?
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 27 Sep 2021 :  20:54:09 Show Profile Reply with Quote
quote:
Originally posted by Derek
Isn't there an earth connection behind the fuse box that can go funky? Remove and check.


Derek.
Ah, wasn't aware of that Derek, will check next time I see the car.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 28 Sep 2021 :  11:20:36 Show Profile Reply with Quote
quote:
Originally posted by Derek
Isn't there an earth connection behind the fuse box that can go funky? Remove and check.


Derek.
Ah, wasn't aware of that Derek, will check next time I see the car.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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UK_Sub
V4 Guru

United Kingdom
2337 Posts

Posted - 28 Sep 2021 :  13:45:31 Show Profile Reply with Quote
As Derek said - the back of the fusebox can getc fairly crusty over time - I cleaned up mine and it fixed a number of issues!
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 14 Oct 2021 :  13:41:39 Show Profile Reply with Quote
Update. Well there's no earth behind the fuse box, but after much fiddling with lamp holders, and bulbs, we now have the charging light and oil light working. Also the temperature gauge seems to be working, still fiddling with the fuel gauge!

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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72sonett3
V4 Fanatic

Spain
264 Posts

Posted - 16 Oct 2021 :  22:15:39 Show Profile Reply with Quote
With contact on, there must be 12 V on both sides of the fuses 1..8.



--
'72 97
'77 96L conv.
'95 900SE conv.
'99 9-3T
? 006
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 24 Oct 2021 :  20:52:13 Show Profile Reply with Quote
Well finally got round to opening a couple of these gauges, and I found that on both gauges, the earth line (Pin 12) on the printed circuit boards had broken, in two places. Same place on both gauges.
See photos below.
Does anyone have any ideas why they would both blow, at the same place?
Perhaps a weak point, or perhaps just because they are all around 40 to 50 years old...

Both of these gauges have been at some time, or another, in my mates car.
We have subsequently got a third gauge, working in situ, in the car.





1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro.

Edited by - andydeans3 on 24 Oct 2021 20:54:51
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Derek
V4 Guru

United Kingdom
2050 Posts

Posted - 26 Oct 2021 :  12:44:11 Show Profile Reply with Quote
Is pin 12 the second one up clockwise on the ring of connections> Should be easy to solder in a small wire link to fix it if that is the case.
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 27 Oct 2021 :  18:03:08 Show Profile Reply with Quote
Derek
Yes, I have soldered wires in to bridge the gaps, I'm just mystified why both of these units should have printed circuit lines burnt out at the same place.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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