My 740 is having issues charging. I had the alt. tested and it failed so I put in a new one tonight and same issue is happening.
The car will start and run off the battery but die when drained. The alt I put in is a remaned, but off the store shelf new. What other issues could this be? All connections are correct and tight.. Please any help would be great.

 

Did you take it back and have them test it?
Because it is off the shelf doesn't mean it is good.

You might also want to check the engine wiring harness and make sure it isn't shorted out.

 

Any advice on how to check the harness..
is there a way for me to test the alt useing a voltmeter while in the car?
Thank tech for the quick responce.

 

The only way to check is to go to the big wire on the back. It should be like 13Volts to 13.40.

You should be able to find the engine harness plug easy. It is a 8 wire plug at the back of the Head.
The engine side is where the sheilding usually falls off. I forget which color is for the Alt.

 

Well it wasnt the Alt.. I took it back to get tested adn it was good..
I'm going to try some new connections at the alt and hope...
Is there method to testing the harness? Never really did that before.

 

Ohming might be able to tell you.
If you can find out what color it is run a new wire.

 

Can I do that.. Would it be possible to bypass the harness and just run a second positive (+) wire right to the battery or do I run the risk of shorting somthing else.?

 

You would have to tap into the engine harness back side for the charging to work.
If you can see the color at the Alt. then find it at the harness plug and run it from there to the Alt.

 

Are there engine wire diagrams anywhere online.. my chiltons just has chassis diagrams...
Its too cold up here to play guessing games

 

Try looking here they only go back as far as the 940. If yours is a later model it might be the same.
I will try to look it up tomorrow as well.

What year is yours?

http://www.volvotechinfo.com/WD123/

 

Thanks tech
its either a 90 or 91 non turbo

 

it looks like something has already been bypassed in this car.. The pigtail that comes off the back of the alt is a single wire running under the dash and is hacked into a blue wire with a black stripe thats part a main connection.
Where should this wire really go? and if this si the bypass you were talking about is this correct.
The car is still only running on the battery.. voltage is comming out fo the alt and the pigtail wire has current runn through it also...
Im really stuck as to what this could be.. I was hopeing to sell this car whole.. I would hate to chop it up over something so stupid.

 

do you have your ground strap connected to the alternator? check that..
by the way ,I was doing a charging test and all of a sudden the ground strap that connects to the back of the alt started to smoke...now it seems that I have an internal short inside the alt. because the whole casing is runing about 7 volts trhough it.. any ideas or sugestions anybody?

 

Im going to try cleaning the ground now.. but it looked good

 

I looked at work today. The engine harness plug will have a red wire in it. Bypass the engine side and tap into the car side.

Oh and one other thing does the battery light come on when you turn the key on?

 

Nope.. is that good or bad

 

That means the circuit for the little wire to the Alt. isn't working. The bulb on the dash complete's the circuit.

I have seen one car that had a burn in the circuit board. A drop of solder fixed it right up.

But still check the Red wire first.

 

well im still plugging away at this...
Im trying to figure out where the short is..
If i wanted to check out the board where exactly is it and how do i get at it?

 

Remove the entire speedo cluster. The back of it is the circuit Board. You should see it once you remove it.