Hello everyone...

My 85yr old friend I go to help out has a 1986 Volvo 740GL.
His old alternator was putting out 15.2v and he was perplexed as to why. He kept driving that way for about 3 months. Now puts out no charge on a Brand New Bosh alternator with new Voltage regulator.

What we have is I touch the multi-meter to the positive on the Alternator, and then ground it on the outside of the Alternator I get 14.52v. (with the alternator ground strap on it).
When I ground it on the engine block I get 12.52v.
Checked the blue ground strap resistants. Also checked to the alternator and under the throttle body connections are good. All is connected and tight, they are not corroded either. I checked the negative battery ground it looks good, and cleaned the contact points. Frame rail and under power steering pump.

Dash battery light comes on and goes off as the vehicle starts up, and D+ on the alternator has 12.5v coming off of it when ignition is in position II...

I am at a total loss if it's just a stupid ground issue, fused link we have no idea.

Any information please please is helpful.

Blessings,
Jim

You have done most of the normal troubleshooting which is good.

You now have I think three electronic paths that need to tested by elimination:

A) Using a jumper cable go from negative battery post to the chassis side of the alternator ground...above battery voltage on your test?

B) Same but negative terminal to clean metal on on the engine.

C) Battery positive to the alternator output lug


By using a separate low resistance wire to run existing paths in paralleled you find the break in the path. My guess would be you have a badly internally corroded lead from the battery.

What is the resting voltage of the battery, engine turned off for at least 5 minutes?

VERY GOOD pointers!!

Resting voltage is 12.2v at 58deg outside when I checked it.
I will grab some new low resistance wire, and make a straight path to the alternator this weekend.

I was about to buy him a 1991 Toyota P/U. But he is sold on tackling this crazy 740.

Keep anymore information coming, this is one of the best Forums!!

Blessings,
Jim
--
2006 Mini Cooper GP | 2007 Evolve V70R Tuned |

I seriously just use a jumper cable...the cheap 8 gauge emergency ones are fine and tend to have smaller clamps anyway.