B230FD Problems :)

[Volvo940GL]

Originally Posted by Laird Scooby

points to a definite alternator fault



How many more ways can i say it??? The alternator is FAULTY!!!!!

Oops sorry, my bad, thanks for letting me know it’s a problem now, and alternators aren’t cheap :/ but hey, guess I’ll buy one if it really needs to be replaced.

[Laird Scooby]

Originally Posted by Volvo940GL

Oops sorry, my bad, thanks for letting me know it’s a problem now, and alternators aren’t cheap :/ but hey, guess I’ll buy one if it really needs to be replaced.

If you still want to upgrade to 100A, now is the time to do it!

Ash - remember that thread that ran longer than the Mousetrap about an early 940 with a B230F that "engine hunts and won't rev" or something very similar?

That ended up being the ECU but it also had a duff alternator, only able to trace the ECU for sure after replacing the alternator but it seems odd that two cars with reasonably similar symptoms both have duff alternators. Wondering if there's a pattern here that a dead alternator can kill a particular type of ECU - what do you think?

[aardvarkash10]

The ECUs are pretty well protected against voltage spike. I can understand the ECU throwing codes if the B+ rail drops significantly - it will start to mess with lots of references.

Had the failed alternator the other day with Moomin. He started to stumble and ran bollocky for about 1/2 an hour. Tacho took on a mind of its own, lights on the dash like Vegas during the summer vacation until in the last mile it was a fight between the ignition system and the fuel system for the last remnants of electrons.

I haven't looked for codes and the check engine light has not come up, but it wouldn't surprise me at all.

I suspect any ECU failure might be coincidence or the result of uninformed "testing"

[Volvo940GL]

Originally Posted by aardvarkash10

The ECUs are pretty well protected against voltage spike. I can understand the ECU throwing codes if the B+ rail drops significantly - it will start to mess with lots of references.

Had the failed alternator the other day with Moomin. He started to stumble and ran bollocky for about 1/2 an hour. Tacho took on a mind of its own, lights on the dash like Vegas during the summer vacation until in the last mile it was a fight between the ignition system and the fuel system for the last remnants of electrons.

I haven't looked for codes and the check engine light has not come up, but it wouldn't surprise me at all.

I suspect any ECU failure might be coincidence or the result of uninformed "testing"

A mechanic told me that if you change EZK and ECU. The MAF needs to be changed to match. But I’m going to test the generator now

[Volvo940GL]

Originally Posted by aardvarkash10

Dave is correct - the alternator warning light on the dash is a part of the charging system.

A couple of things to confirm Dave's diagnosis please.

Start and run the car with the headlights on, heater fan running, stereo on, any other electrical thing on that you can get.

With your multimeter set to Volts DC, put the positive lead of the meter on the alternator output terminal (the big red wire) and the negative lead of the meter on the battery positive terminal.

Bring the engine up to about 2,000rpm, and read the voltage on the meter. It should be less than 0.5v.

Switch everything off, and then come and tell us what teh reading on your meter was. Do nothing else.

Started the car with heater on, geadlights, stereo heater,

It shows 0,28v

Battery shows 11,88v

[Laird Scooby]

Originally Posted by aardvarkash10

The ECUs are pretty well protected against voltage spike.

I suspect any ECU failure might be coincidence or the result of uninformed "testing"

They are fairly well protected Ash but there are certain ECUs that have shown themselves to be susceptible to failure from being disconnected and reinstalled and/or disconnected without removing the battery earth first. This, if memory serves, bears the same number (ends in 984 i think it is) so could be a "fragile" one.

Originally Posted by Volvo940GL

Started the car with heater on, geadlights, stereo heater,

It shows 0,28v

Battery shows 11,88v

That was at 2000rpm?

[Volvo940GL]

Originally Posted by Laird Scooby

They are fairly well protected Ash but there are certain ECUs that have shown themselves to be susceptible to failure from being disconnected and reinstalled and/or disconnected without removing the battery earth first. This, if memory serves, bears the same number (ends in 984 i think it is) so could be a "fragile" one.




That was at 2000rpm?

Yeah, 2000rpm

[Laird Scooby]

Originally Posted by Volvo940GL

Yeah, 2000rpm

Oh dear.

Oh dear, oh dear.

Oh dear, oh dear, oh dear.

The charge warning light was on during all this as well?

[Volvo940GL]

Originally Posted by Laird Scooby

Oh dear.

Oh dear, oh dear.

Oh dear, oh dear, oh dear.

The charge warning light was on during all this as well?

Yes, it’s always on constant

[Laird Scooby]

Time to replace the alternator from the sound of things. May as well try to find a 100 or 120A unit while you're about it....................