S70 Anomaly Stalls Restarts

ez4u · Post by **ez4u** » 25 Dec 2011, 09:44

Hi,
Did a search but couldn't find anything....don't even know where to start...any help/advise will be greatly appreciated....

S70 with 170K, no check eng light & no codes.
Car starts normally, then suddenly stalls dead! Seems like an absoloute electrical failure. The instrument cluster goes completly blank and will not start, no crankin, no noise ..only dead silence (all the normal lights that u see with the key switched on are off). Then the odometer and the clock shows..888888888 ... like it's doing a self test or something (all instrument cluster light still dead and no cranking, like a dead battery). After about 6-10 seconds later the 888888's disappear, and everything returns to normal. And the car starts.

This has heppened in the morning when the car was cold, and it has happened stittling in traffic.

Any ideas?

Post by **JDS60R** » 25 Dec 2011, 10:55

Sounds like a bad battery or failed/failing battery cables. There is a known flaw where the main power line feeds into the fuse box.
https://www.matthewsvolvosite.com/forums ... =1&t=35208

Post by **burnout8488** » 25 Dec 2011, 11:47

JDS60R's diagnosis sounds pretty feasible. What year and trim is your car?

ez4u · Post by **ez4u** » 02 Jan 2012, 19:53

1998 S70 non turbo 170K.
Well, ...didn't think it was the battery but replaced it anyway to make myself feel better. (It would restart right away, tested by repeating several times. I even left the seat heat and lights on for ten minutes on battery alone and then restarted). Cleaned the terminals ...checked around...everything looked ok. Run a backup line from the battery to the fuse box as recommended by that other post that was linked above.

The car would lose ALL electrical pwr at once and die. Even had to reset the radio code after the anomaly. So I guess we'll see if I happens again. ... Any ideas?

Post by **jblackburn** » 02 Jan 2012, 21:59

Run a backup line from the battery to the fuse box as recommended by that other post that was linked above.

That's unclear to me...have you done this or not?

That's where I'd go next if you haven't. Sounds like the battery cable is crapping out under load...this happens pretty frequently, especially on 1999 and 2000 models.

ez4u · Post by **ez4u** » 03 Jan 2012, 05:07

Yes I have run a backup line from battery to the fuse box.
However, I don't see how it could be the battery cable that is going bad? The battery cable goes from the battery to the starter...why would this cable cause sudden death? Especially after the car has been started? Unless I'm missing your point....
Thx

Post by **jblackburn** » 03 Jan 2012, 07:03

The fusebox one is usually what causes this to happen - a high amp draw goes through that line when accessories, etc are on. When the cable heats up too much, it acts like a kink in a garden hose - causing electrical systems to shut down and your car to die.

You could try running another from the alternator over, or at the very least testing resistance on that cable (you should get a very low resistance).

If the cables test out, I might look to either:
1) The fuel pump relay, or
2) Cam position sensor

ez4u · Post by **ez4u** » 03 Jan 2012, 13:29

Sounds like a great plan.
Electrical diagnostics is my weakest trait (..among a few others..).
Q1: what kind of a tester should I get? There is a Lowes, Homedepo, Wal-Mart etc nearby.
Q2: During start, current is drawn OUT from the battery, but then after the alternator kicks in...current flows from the alternator through the battery and then to the fuse box and all other systems....is this correct?
Q: When a cable/line goes bad the resistance drops right?...why?

Thanks

Post by **jblackburn** » 03 Jan 2012, 13:36

Correct on 2.

Resistance will INCREASE when the cables go bad. If you see something over a few ohms, that cable is beginning to go bad. Sometimes corrosion at the end is responsible for this - in that case, you can take a wire brush and clean up the contacts real well.

I'd head to Radio Shack if you have one and buy a simple digital voltmeter. I've had one for 10 years and it still works just fine. Actually very similar to this model:
http://www.radioshack.com/product/index ... Id=4214667

bronco · Post by **bronco** » 17 Jun 2021, 09:14

This just happened on my 1998 V70 and I searched and found this thread !

I checked the bundle of wires from the positive cable and they looked ok so I went to wiggle the relay and the yellow out cover was loose and came right off

I switched the airpump relay with it to see if the problem continues . It appears to be the same part and the air pump is long gone so it doesn't need anything in that spot . Or at least I don't think it needs it