7710 charging problem

MNfarmer · Dec 2, 2016

My 7710 doesn't charge, it only had 12 volts at the battery while running. The battery light doesn't come on so am I better off to chase the electrical to the light or the battery sensor or just put a delco Remy alternator on it?

Bern · Dec 2, 2016

You're always better off with a Delco in place of that Lucas POS. Question is, do you want to spend the money and time? The issue with the Lucas could be as simple as worn brushes. These are easily checked by removing the regulator on the back of the unit. The regulator and brush set are an assembly.

Another common issue with the Lucas is the battery temp circuit. If this circuit is open (e.g. faulty sensor), it will not charge.

sotxbill · Dec 2, 2016

llast week... problems with the plug on the back of the alt being loose and pulling back...push it in good and its charges.. drive it around a bit and it quits,, till pushed back in again. might have been a clip there or something but its gone on that one. Put a delco on it and never looked back. It was a lucas internal reg model with two heavy wires and one small wire on the plug.. thing is.. .that the second heavy wire was the bridge to the cab power feed so when the plug moved back.. the a/c cut off as well as throwing a alt light.

rvirgil_KS · Dec 2, 2016

Fix the light first. It "jump starts" the alternator when engine is started. Without the lamp a Delco will also not charge.

If you do change to Delco alternator, get the 3 wire not the 1 wire. Loop #2 edge connector to charge output and connect your lamp wire to #1 connector.

If you use a 1 wire alternator you will lose the warning function of the indicator lamp.

Non working lamp will likely be either a burned out lamp or bad wiring connection

JMOR · Dec 2, 2016

(quoted from post at 11:52:50 12/02/16) Fix the light first. It "jump starts" the alternator when engine is started. Without the lamp a Delco will also not charge.

If you do change to Delco alternator, get the 3 wire not the 1 wire. Loop #2 edge connector to charge output and connect your lamp wire to #1 connector.

If you use a 1 wire alternator you will lose the warning function of the indicator lamp.

Non working lamp will likely be either a burned out lamp or bad wiring connection

Without the lamp a Delco will also not charge. " True ONLY when installer took a short cut & failed to do it the way GM did.

MNfarmer · Dec 2, 2016

Thanks for the info everyone. Right now it has a denso alternator on it with four wires going to it. The main power wire, a black wire going to another terminal and two smaller wires that are connected to connections on the back. If I go to a self energizing delco should I just tape over the ends of the other wires?

RodinNS · Dec 2, 2016

Check the bulb first. If that's good and it still won't light up with the engine not running... then I'd look at the bulkhead connectors under the cab. Those are notorious for crumbling so you may find the open there.
Also check the wires at the alt as that's easier than the bulkhead...
If the problem is the alt, definitely change to a 3 wire Delco. It will take a bit of work to fit but it's well worth it...

Rod

MNfarmer · Dec 2, 2016

Thanks Rod. The bulk head connectors you mentioned, are they on the cab itself or the connectors in the wiring harness between the cab and the engine?

RodinNS · Dec 3, 2016

The harness connections under the cab.

Rod

MNfarmer · Dec 13, 2016

Here's the alternator I have. I'm wondering which is the exciter wire? I know one of them is unhooked in the picture, I was checking the connections and forgot to hook it up before taking the picture. Will it work to use a jumper wire to the exciter circuit until I figure out what's causing the issue??

7710 charging problem

MNfarmer

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Bern

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sotxbill

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rvirgil_KS

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JMOR

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MNfarmer

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RodinNS

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MNfarmer

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RodinNS

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MNfarmer

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