1993-240: Electrical SNAFU

93Regina · Post by **93Regina** » 27 Mar 2015, 20:58

Key On - No Warning lights

Engine Idling - A dim battery light, fuel/temp gauges do not work...battery voltage 13.8V

40 MPH Driving with OD engaged - Speedometer reads 20 mph

40 MPH Driving without OD - Speedometer reads Zero, battery light bright

93Regina · Post by **93Regina** » 28 Mar 2015, 11:13

Update:

After taking a 10 mile highway drive, I disengaged OD, and fuel/temp gauges began working, and speedometer went to traveling speed.

Back to normal now!

I fail to see how that OD Relay is related to this SNAFU, but somehow it is.

lummert · Post by **lummert** » 28 Mar 2015, 11:30

Does this car have a main head light relay similar to the one used on 88-90 760 and 92+ 960? The main relay on my 88 760 is rectangular about the size of two standard relays. When this relay was failing on my car I had all sorts of electrical problems. The head lights randomly wouldn't come on, the speedometer would randomly stop working when the head lights were on. The overdrive light would be lit even though it shouldn't have been. Replacing this relay with a spare solved the problem.

93Regina · Post by **93Regina** » 28 Mar 2015, 12:32

lummert wrote:Does this car have a main head light relay

Several months ago, I replaced this relay with a VOLVO 1307991 GENUINE OEM RELAY

When I clicked the OD button to disengage, it was instantaneous, everything back to normal.

Quartz clock worked fine, all of the time.

93Regina · Post by **93Regina** » 10 May 2015, 20:22

lummert wrote:Does this car...

Symptoms:

1. OD Engaged - OD and battery lights were dimly lit; No temp reading, and a pinch on fuel gauge
2. When key switched to on position, all warning lights off.
3. Non OD Mode - Only battery light glows brightly, nothing else works on dash except clock.

Solution - Maybe fuse 16 was the issue. I cleaned its terminals, and fuse's ends

16 Parking lights (right side), Instruments and control panel lights, Shift indicator light 8A

93Regina · Post by **93Regina** » 17 May 2015, 10:48

Back to square one....today, issue lasted for seven miles of driving, and then everything OK.

5ft24 · Post by **5ft24** » 25 May 2015, 12:30

Check grounds to the instrument cluster

93Regina · Post by **93Regina** » 25 May 2015, 15:55

5ft24 wrote:Check grounds to the instrument cluster

That's an idea....I need to study/think about that OD Relay...when issue happens, it is dimly lit with OD engaged, and brightly lit when OD is off.

OD Relay provides a ground path for bulb to light up when OD is not engaged, which would suggest there is power on the bulb side.

Alternator light is lit up when this issue happens, which would normally mean the alternator is providing the ground path.

One of these days, I'm going to remove instrument cluster and fix Odometer.