Electrical problem 1985 740

Good day,

I have some sort of electrical problem with my 85 740 (and who
hasn't?).

The other day I noticed that all the indicators did not come on when I
turned the key. The car did start however.

All that comes on is the up-shift indicator, the oil pressure warning
light and the seat belt indicator.

Drove the car that day.

Next battery was dead. Still there is an issue with indicators. I
assume battery is not getting charged.

Charged battery cleaned battery terminals and small ground to chassis
and car started. Disconnect the small ground wire and the car will not
run.

Indicators are still not right.

Battery and alternator are both fairly new. Failure of either of these
would not affect the indicators once the battery was charged.

I can hear what I believe to be a relay clicking under the center
console (seat belts?).

Seems like I have lost ground somewhere.

Before I start tearing the dash board (facia) apart…

Where are the grounds in this car? Where does the instrument cluster
get ground? Where does the electrical panel (relays and fuses) get
ground?

Is there another chassis/body ground?

What would cause the battery to die (or more probably not get
charged)?

On cold days, indicators take a while to come on. Car will not start
until indicators come on (I suspect that is normal). Changed fuel
filter and delay seemed less.


TIA

jimB

 

You could check the chassis/body ground near the head lights.

 

Try moving the key back and forth just a little bit in each direction.
If the contacts don't line up just right in a worn igniton switchnthe
dash lights don't come on. Alternatively if the ground wire from the
instument cluster isn't making contact the lights won't come on.

Bob

 

Bob

I will try that again.

I am concerned about why the battery went dead and I am assuming that
the issue with the indicators is related and not a coincidence.

Given what I know about Volvo electrics, I need to locate and check
all grounds.

Instrument cluster and relay panel mainly.


jimB

 

The missing warning lights are all turned on at the same time as the amp
(aka battery) light. If the alternator fails in a certain way, not only
will you get no warning lights, you'll get no charging. This seems to
be what has happened in your case. This may require only brushes, the
whole voltage regulator, or the whole alternator, depending on what has
failed. Also check the thin red wire at the alternator, as well as the
thick blue ground wire.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
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