No battery dash light- No battery charging (help please)

[QuadcityDMC]

Ok. Back in October 2015 I changed my altanator, belt and battery, drove the car till late Dec. had it back out and driving from March till now.

Noticed battery light flicker when the ignition was on back in October so that's why this was replaced. Also it was replaced back in 2011 during a Creat Stage 2 Engine install. Oh and I new starter was installed 2014.


Today- found the terminal wires to the altanator (6 brown wires) grounded to the altanator case- removed and put new heat shrink on and reinstalled. Switched the battery light in the dash with the fuel light (for testing) the oil light is currently removed from the dash. Battery light is normal bulb and fuel light is normal bulb everything else is led.

Oil sender wire looks rough and the gage will run backwards but it moves. (Do all the lights need to be in the dash to complete the circuit?)

Just turned the car on, no battery light and 12v at the battery so the altanator is not charging.

I have looked in my books and read some threads of similar problems.

[David T]

Remove the alternator and have it tested. Most places will test it for free.

[QuadcityDMC]

I hope it is that simple.

[DMCMW Dave]

Disconnect the small brown wire from the alternator. Connect the wire (not the alternator!!) to ground. Turn the key on. If the light goes on, it's an alternator problem. If the light does not go on, you have a problem in the light circuit, either the bulb, the binnacle connector, or the bulkhead connector near the coil. The light must work for the alternator to charge.

[QuadcityDMC]

Thanks I will do that. Now just to be clear - unplug the connector from the altanator with the single brown wire and ground it to a ground wire.

[DMCMW Dave]

Thanks I will do that. Now just to be clear - unplug the connector from the altanator with the single brown wire and ground it to a ground wire.

Yes, that's the one.

Quick theory of operation - the other side of the bulb is connected to switched 12V (in the dash) from fuse #5. If the alternator is not spinning, the alternator end of that wire is grounded internally. So the light goes on. BTW that same fuse powers the oil light, brake light bulb, otterstat, and voltmeter, so if those are working it's not the fuse.

When the alternator spins up, the alternator wire goes to 12V, which means the bulb now has 12V on both sides of it so it does NOT light up.

Grounding the wire at the alternator end should make the light come on when the car is turned on.

[Jonathan]

Yes, that's the one.

Quick theory of operation - the other side of the bulb is connected to switched 12V (in the dash) from fuse #5. If the alternator is not spinning, the alternator end of that wire is grounded internally. So the light goes on. BTW that same fuse powers the oil light, brake light bulb, otterstat, and voltmeter, so if those are working it's not the fuse.

When the alternator spins up, the alternator wire goes to 12V, which means the bulb now has 12V on both sides of it so it does NOT light up.

Grounding the wire at the alternator end should make the light come on when the car is turned on.

Wow, nice explanation Dave. Retired or not, you STILL the MAN!!!

[content22207_2]

Quick theory of operation

Dash indicator wire also excites the alternator field, allowing it to start charging immediately (low RPM's; most alternators will charge OK at high RPM even without field excitation).

In the bad old days you sometimes had alternators with field excitation wires that had to be switched on and off manually (old International Harvesters were like that. Some old tractors too). Being wired to ignition on modern cars switches excitation on and off automatically.

Bill Robertson
#5939

[QuadcityDMC]

Light came on when I grounded the plug. So it looks like a new altanator for the car. Is there a warranty on the altanator from DMCH? I'm sure I got it back in October. Thanks for the help Dave.

Oh and Case IH factory was in my home town, closed in the late 80's and now they want to build a water front where the factory was. If the EPA ever tests the ground they will need to dig it all up because of the oil from the production line.

[BABIS]

Disconnect the small brown wire from the alternator.
not the brown yellow wire? (or at least in the "ducy" wiring arrangement)

[DMCMW Dave]

On the dulcy it is the one with the yellow stripe. Don't ground the sold brown one!!!


Sent from phone

[QuadcityDMC]

I grounded the brown /red or pink and the light came on. The old plug from the factory is still in the wiring loom. I installed the new altanator per DMC instructions that came in the box. It's the $200 one off the website.

[Ron]

Dash indicator wire also excites the alternator field, allowing it to start charging immediately (low RPM's; most alternators will charge OK at high RPM even without field excitation).

In the bad old days you sometimes had alternators with field excitation wires that had to be switched on and off manually (old International Harvesters were like that. Some old tractors too). Being wired to ignition on modern cars switches excitation on and off automatically.

Bill Robertson
#5939Actually, voltage on the the dash indicator wire excites the Voltage Regulator, which controls the voltage input to the Rotor, which creates the field.
Nowadays, most voltage regulators (including the Delco type replacements for Ds) are self-exciting. Once you rev the engine, they will kick in and perform normally.

[DMCMW Dave]

I grounded the brown /red or pink and the light came on. The old plug from the factory is still in the wiring loom. I installed the new altanator per DMC instructions that came in the box. It's the $200 one off the website.

Next step to make sure is to take the alternator off the car and have it tested (Autozone for free) before you send it in. Or contact the seller and get it replaced/repaired. It's most likely defective. It's under warranty.

[QuadcityDMC]

Will do. But my dealer retierd a few months ago. ;-). I just ordered a few parts from Mike last week and talked to his wife.

[QuadcityDMC]

I have the car back up and running thanks the Dave and Mike at DMCMW. I still have a flashing battery light when the key in set to on. Could that be caused by a bad connection of the *new* alternator brown wire to the wiring harness?

[Bitsyncmaster]

I have the car back up and running thanks the Dave and Mike at DMCMW. I still have a flashing battery light when the key in set to on. Could that be caused by a bad connection of the *new* alternator brown wire to the wiring harness?

I had the flashing light with the new DMCH alternator. When I connected the alternator "S" terminal to the battery lug it stopped that flashing and stop the very quick voltage dip every 18 seconds. So I guessing that flashing is a warning indicator.

http://dmctalk.org/showthread.php?12181-DMCH-alternator&highlight=alternator+voltage

[DMCMW Dave]

I had the flashing light with the new DMCH alternator. ]

Yes, they do that.