Any way to test alternator?

[Laird Scooby]

What is it (740/940. engine, year etc?) and did the charge warning light work when you first got it? Or any of the warnings lights come to that?

[cheshired5]

In case you missed me asking it earlier.....

Originally Posted by cheshired5

Have you checked the diodes?
There's more than one reason for low volts.....

[Sheehan879]

Diodes were checked and the lights have never worked. Will put the recon alternator on tommorow and report back.

[Laird Scooby]

Originally Posted by Sheehan879

Diodes were checked and the lights have never worked. Will put the recon alternator on tommorow and report back.

Is that the one that previously got hot?

[Sheehan879]

Thanks for all your help, after getting a 2.4 turbo alternator that didn't fit I eventually got a 2.0 NA recon unit and all is now well. Even my dash lights come on now, not sure what effect the alternator has on dash lights but there you go.

[Laird Scooby]

Originally Posted by Sheehan879

Thanks for all your help, after getting a 2.4 turbo alternator that didn't fit I eventually got a 2.0 NA recon unit and all is now well. Even my dash lights come on now, not sure what effect the alternator has on dash lights but there you go.

As previously mentioned, you need the field circuit (warning light) working for the alternator to charge. Many of the other warning lights in the panel come on when there is a "no charge" situation as a self test.
Because the no-charge situation didn't bring the charge warning light on, the electronics supplying the other warning lights for self-test would not have powered up, hence no other lights.

All the evidence was there from the start.

You've learned a fair bit about your car including the fact that Volvo didn't make the 2.4TIC diseasel unit, it's a VW engine. That's why the alternator didn't fit.

The 2.0 n/asp alternator might be lower output than you should have on your car but we still don't know what model, trim or engine you have in yours. It would have made diagnosis easier!

[Sheehan879]

I am back to square one, the new alternator seemed to do the trick, all the dash lights started to come on including the battery light. Got in today and no lights apart from the seatbelt warning. I checked with a fluke and the alternator is not charging again.

I am thinking instrument cluster, I removed it but all looks fine. Can I test the instrument cluster?

[Laird Scooby]

Something i had on one of my 740s was the connectors in the plugs that plug in the back of the instrument cluster were all dirty and the springiness of the contact fingers had subsided over time.

I removed the cluster, went through each contact "finger" on each plug (where it connects to the PCB on the back of the cluster when the plug is pushed in) and eased it up to make more of a curve (you'll see what i mean when you look at the plugs) and cleaned each one and also the PCB with some very fine emery cloth - don't use sandpaper!!!

Plugged it all back and tried it, job done! Also might pay to check the bulb in the charge (battery) warning light is making a proper connection in the bulb holder. It's a higher power bulb than the others usually to provide the current the alternator field needs but should be a maximum of 3W - don't put anything bigger such as a 5W in as you could easily damage the alternator.

Also check the connections to the alternator.