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Discussion Starter #1
Hey folks,
I have a battery light on dash that is on because the alt isn’t producing the voltage at the respective terminal that the cluster is looking for. Think I measured 1V, 14.5ish at the batt cable.

Wondering if I can add the DC sense wire to the cluster to the battery post on the alternator? I’m afraid of frying something is why I ask.
I also don’t know if this is the factory alternator because someone cut off the factory plug and wired it up with clamps.
It is a 2 wire alternator and figure I pull power from somewhere else for the cluster than to pull off the alt.

TIA
 

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Discussion Starter #3
Yeah that’s the DC sense wire I speak of. Trying to wire it to the batt terminal on alternator instead of where it goes because the terminal that it should go to on the alt isn’t producing a voltage.
 

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May not be the wire then. Ecu should cover what the alt does and if it’s out of spec, it should trigger the light.

But you be able to bypass that with a wire. Idk.
 

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Discussion Starter #7
Yeah so the cluster via the PCM probably since I dont have the diagram memorized needs to see that the alt is producing via a brown wire at the alternator. The other wire in that harness is the signal wire that basically tells the alt to turn on.
so the alt turns on but the other terminal on the alt for the pcm/cluster has no voltage so the battery light comes on the dash with the wonderful beeps and check alt message.

Sooo, if I use the fat battery cable terminal off the alt I should be able to make the check alt message/light go away, right?
 

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Discussion Starter #9
Sure. Worth a shot. Where are you checking the power for the other pin? At the harness near the battery right?
checking for power at the source, the second terminal of the alternator.
Meter from there to engine ground =0V.
Meter from alt battery terminal to ground = 14.5V.
 

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Stop.

If you have an 05 or 06, your alternator gets a duty cycle command and an on/off signal from the ECM. It doesn't work like older alternators.

Running a wire from the battery will do nothing but fry your alternator electronics at worst, nothing at best.
 

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Discussion Starter #12
Brochacho. Did you miss my redlined schematic? I’m proposing to move the cluster wire from the terminal on the alt where it should be to the battery terminal on back side of the alt just to get a voltage reading to the cluster and shut off the check alternator warning.
 

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FWIW, if your alternator is charging, i would check for any blown fuses in the underhood block, and in the driver knee panel block.

If you have a scantool, see what the ecm reports the voltage as.

I will check the service manual for where the 05/06 cluster alt/batt light works when i get home. It either reads voltage from a circuit (hence checking the fuse panel) or gets it from serial data.
 

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Just a guess here, but looking at the pdf file for the 2005 wiring, check the 7.5a heated rear window fuse and the 10a instrument fuse.

The 7.5a heated rear window fuse is listed at "low reference" for the instrument panel.
 

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Discussion Starter #16
K. Both of those fuses are good. I didn’t find a fusible link in either wire coming from the battery, pic attached of a brown wire coming from what seems to be either of positive cables harness but it doesn’t have power
besides my issue is with the cluster wire not the wire that feeds the alt 12V and I know the alt is working so no point in chasing that unless the cluster is fed by the DC sense wire, which I don’t believe it is.
I really think the alt should be sending voltage out of its B terminal to the cluster which is why I thinking feeding it with any battery voltage would suffice for the issue.
 

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There is no fusable link inline on the b+ cable. The only fusable links are attached to the positive bus on the engine fuse block, iirc.

The wiring diagram doesn't show a DC sense wire. Both L and F terminals go to the ECM, unless the pdf service manual is wrong, which it has been before.

Let me look at my own harness and the service manual when i get home. The wiring diagram on my phone doesn't show much, and the pdf service manual has ben wrong before.
 

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Discussion Starter #18
And down at the alt, here’s what I think will work but am afraid it’ll blow the cluster/pcm being that it’ll get full beans from the alt. Might have to add a fuse in line to be safe.

So in the pic the wire crossed out is the terminal b wire that goes to the charge indicator lamp.

the next terminal is the DC sense terminal. If I understand this mechanism correctly this is what is needed toget the alt going and output via the bigger wire to the battery.
 

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