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940 Turbo no electric power

xallenx

xallenx

Member
Joined
Sep 1, 2003
Location
Charleston, SC
Hi,

I was backing out of my driveway and all
of a sudden the car shuts down. I tried to re start but no power. It’s acting like I took the entire battery out. I tried jumping but no luck. The battery is good. Help!!
 
Do you have any aftermarket electrics in the car? I have this issue if I put the e-fan in my 944 on before starting the car, or if I click it on before the alternator has had time to spin up - the fan just eats all the battery power and it either shuts off or I get every warning light on the dash.
 
fatcatbestcat said:
Do you have any aftermarket electrics in the car? I have this issue if I put the e-fan in my 944 on before starting the car, or if I click it on before the alternator has had time to spin up - the fan just eats all the battery power and it either shuts off or I get every warning light on the dash.
Click to expand...
No, aftermarket electrics of any kind. Plan to swap battery just to see after work.
 
Since the battery is good check the Positive and ground cable connections to the starter and chassis. Then the little power distribution box on the fender, if 940's have one. After that check for power on the high side of the fuses. It would help if you have a multimeter and Volvo shop manuals with wiring diagrams.
 
Sounds like the battery cable is bad, but the alternator should have kept the engine running. Start checking things with the probe light if the new battery doesn't fix it.
 
As others have said, if you have absolutely zero power immediately after a start up, check the battery ground. I've seen batteries have a break in the circuit internally. You could jump it but it would die the second you disconnected the jumper cables.
 
UPDATE!! It was the battery. She cranked right away after swapping it with a good one. I think the alternator might be done for. What is the Voltage suppose to be when the car is running? I got 13.8v
 
xallenx said:
UPDATE!! It was the battery. She cranked right away after swapping it with a good one. I think the alternator might be done for. What is the Voltage suppose to be when the car is running? I got 13.8v
Click to expand...
Around 14v from alternator when car is running is pretty normal. 12v would mean the alternator isn't giving you charge.
 
13.8v is a little on the low side for a modern battery to take a full charge. See what the voltage is when blower fan, lights, wipers, stereo are all on. If it's lower than 13.6v when you do that it's on the cusp of failure. These modern batteries are happiest with a good 14v charge or more. Some of the new regulators are set to 14.4v for example.
 
Another update. So, I took the suppose to be bad battery and just for fun I installed it on my other car and guess what. The other car started right up. I then took that battery and re-installed it to my 940 and it started right up. WEIRD!!!
 
You probably got connection issue with one of the battery cables. Pretty weird that you can start the car but a minute later it can not run off of the alternator and dies and can not even power the lights and the clock from what you are saying.
 
Not enough info. Take measurements in more places while flexing the connections.

When the engine won't start, check continuity of alternator case to engine block and engine block to chassis. Ignition pulses also turn on (or off) the fuel pumps. Check for ignition pulses when cranking with a clamp-on timing light. Check on coil wire, and or, plug wires.

The ignition key electrical contacts may also be loose. Check for voltages at the fuses.
 
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Yeah, plan to take a closer look at my cables. I did a resistance on both and it’s zero. I think I’ll try wiggling the cables to see if the car shuts off.
 
dl242gt said:
13.8v is a little on the low side for a modern battery to take a full charge. See what the voltage is when blower fan, lights, wipers, stereo are all on. If it's lower than 13.6v when you do that it's on the cusp of failure. These modern batteries are happiest with a good 14v charge or more. Some of the new regulators are set to 14.4v for example.
Click to expand...
13.8 is typical with a Bosch alternator if the battery is fully charged.
 
dl242gt said:
13.8v is a little on the low side for a modern battery to take a full charge. See what the voltage is when blower fan, lights, wipers, stereo are all on. If it's lower than 13.6v when you do that it's on the cusp of failure. These modern batteries are happiest with a good 14v charge or more. Some of the new regulators are set to 14.4v for example.
Click to expand...
You are right!! I turned all of what you mentioned above and checked voltage. It dropped to 13.5. Time for anew alternator!!
 
Check your brushes and diode trio as well. If you have a Bosch alternator you can still get brushes, regulators and trios. Can't speak for denso
 
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