Electrical problem 940

[Ammorack]

Lately my 1994 940 B230fd got problems with the electricity or something like that. When I turn off headlights, the engine starts to go rough and doesn't like it. So is the heater for rear window.

Whatever it is. It’s driving me crazy.

[360beast]

Do you mean when you turn the headlights on?

Sounds alternator related to me

[Ammorack]

Originally Posted by 360beast

Do you mean when you turn the headlights on?

Sounds alternator related to me

I mean when I turn my headlights ON. The rpm is more stable with load on. I had to drive with heater on rear window and heater fan on max to have stable rpm. But now my rpm is everywhere and it’s backfiring and too rich and lean mixture

[Laird Scooby]

You have a serious problem there that you're unlikely to find by yourself, even with our help.

Why did you mess about with the TPS? It's nothing to do with the charging system, neither is anything else you've changed but you don't seem to have changed the alternator?

First of all, do you get the charge warning light when you first turn the ignition key to position 2 without starting it?

[Ammorack]

Originally Posted by Laird Scooby

You have a serious problem there that you're unlikely to find by yourself, even with our help.

Why did you mess about with the TPS? It's nothing to do with the charging system, neither is anything else you've changed but you don't seem to have changed the alternator?

First of all, do you get the charge warning light when you first turn the ignition key to position 2 without starting it?

I do get the charge warning light on KPII
I tested another alternator from a 940. It made the engine worse. It wouldn’t rev past a certain limit. I knew that answer would come. This nut is hard to crack.

[Laird Scooby]

Is that certain limit about 3000rpm and when it gets there, does it die and then rev up again?

[mocambique-amazone]

Originally Posted by Ammorack

Lately my 1994 940 B230fd got problems with the electricity or something like that. When I turn off headlights, the engine starts to go rough and doesn't like it. If this apears only for a short time, 1-2 seconds, and the engine will run later "normal" you shouldn't take care about this. Standart at a sensible running engine. If everything is ok Volvo 740/940 have a "tick" to do this So is the heater for rear window.

Whatever it is. It’s driving me crazy.

jump in Voltage, stop beeing crazy

good luck, Kay

[Ammorack]

Originally Posted by mocambique-amazone

jump in Voltage, stop beeing crazy

good luck, Kay

Could it be the cable from alternator to battery? Or groundingpoints? Alternator regulator are new. Battery is 13,85v, alternator 14v
Battery 12,8v without ignition.

[Laird Scooby]

Originally Posted by Ammorack

Could it be the cable from alternator to battery? Or groundingpoints? Alternator regulator are new. Battery is 13,85v, alternator 14v
Battery 12,8v without ignition.

Check the alternator earth strap, these often fail, even if it looks alright. You'll probably find the missing 0.15V between the alternator casing and the engine block with your voltmeter, indicating the earth strap is failed/failing.

[Ammorack]

Originally Posted by Laird Scooby

Check the alternator earth strap, these often fail, even if it looks alright. You'll probably find the missing 0.15V between the alternator casing and the engine block with your voltmeter, indicating the earth strap is failed/failing.

The problem is that I don’t find the ground for engine.