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Virtual Wrench
Virtual Wrench, Chevy Mechanic
Category: Chevy
Satisfied Customers: 14620
Experience:  35 years Master Mechanic
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1989 GMC pickup wiring diagram for charging system

Customer Question

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Submitted: 9 years ago.
Category: Chevy
Expert:  Virtual Wrench replied 9 years ago.

Hello,

Here is the wiring diagram for the charging system for you.

graphic

 

 


If you have further questions on this, please feel free to reply.

Happy New Year!

 

Virtual Wrench and 2 other Chevy Specialists are ready to help you
Customer: replied 9 years ago.
Where does conections F, S and P go to from voltage regulator? I already new where L goes.
Expert:  Virtual Wrench replied 9 years ago.

How many wires are on the connector that plugs into the regulator?

Customer: replied 9 years ago.
Three
Expert:  Virtual Wrench replied 9 years ago.

Thats wierd,,,i checked another source and its showing just the brn wire...sure its a 1989?

 

Customer: replied 9 years ago.
Yes, 1989 GMC 1/2ton pick up with a 350 V-8 5.7
Expert:  Virtual Wrench replied 9 years ago.

Thanks,

I dont know whats up with my referance data, but thats all i have.

I will open your question up for others in the event someone has something different.

Customer: replied 9 years ago.
okay, thanks
Expert:  Virtual Wrench replied 9 years ago.
Just leave your question open and if someone can help, they will email you.
Customer: replied 9 years ago.
Okay, please leave my question open. Thanks
Expert:  Virtual Wrench replied 9 years ago.

It is :-)

Wait for someone to reply

Customer: replied 9 years ago.
Still waiting
Expert:  Virtual Wrench replied 9 years ago.
Hi, what color are those wires on the connector that plugs into the regulator?
Customer: replied 9 years ago.
It's a replacement plug so all the wires are black. Thats what I'm trying to figuere out where they go.   I have a Brown, Green and a black with a white stripe wire in the vehicle wiring harness?
Expert:  Virtual Wrench replied 9 years ago.

Thanks,,,that definatly helps,

In the harness going to the alternator, the brown wire is tied into the "L" terminal which is basicaly a line feed to the gauge.

The green wire is attached to the "F" terminal,,,,,it is what is called the exciter wire,,it excites the field windings in the alternator only when the key is in the "crank" position,,,this activates the windings, and also allows the vehicle to shut down when you turn the key off.

the blk/wht, i'll have to check.

In other words, if the field windings were to be continously applied with battery voltage,,,the vehicle wont turn off.

Do you have a voltmeter that we can do some circuit testing?

I think we can isolate it pretty quick if you do,,,,this is probably one of the most direct charging systems, and if you understand what i said about the field windings with the excite from the ignition switch, just let me know...i'll be happy to help.

 

 

Customer: replied 9 years ago.
That helps alot. If you can find out what the black with white strip is for, that'll take care of my question.   Thanks
Expert:  Virtual Wrench replied 9 years ago.

No problem bro,,,i just didnt want to see your question hanging out there for too long..

You can continue to ask me questions as long as ya like,,,no prob here,,,it's just pretty cool that i can help people online..."The wonderful world of internet"

I'll search before and aft of '89 for the GM wiring,,,but i got to tell ya,,most all work off the same applied "excitement" to the field windings when the key is turned to the "start" position....

Remember that the field windings at the alternator are excited from a "momentary" pulse of voltage only when the key is in the crank position. once the key is released to the "run" position,,,,,,,,,,,,,,,,the field windings no longer need excitement.........and power HAS to be released from the feild windings("F"), otherwise the engine wont shut off when you turn the key off.

 

 

Keep me posted..

Happy New Year!

Customer: replied 9 years ago.
I'm good to go now. Thanks for your help, it's been a long road to find out what goes where.
Expert:  Virtual Wrench replied 9 years ago.
Thanks for asking!