Where is the ALT idiot light on 1988 burb?

[Frankenchevy]

Generally on a CS alt. "L" or "I" is used as exciter (BRN 25 wire) And "S" (sensing) is usually red.

I’m curious - Check your alternator and see if the terminals are labeled like the connector.

Terminals are labeled the same. Did a continuity test to see if I could trace the wires to the volt meter. Pink wire in the FIELD position traced back to the pink highlighted terminal on the volt gauge socket, but that could simply be that they are common at the hot side of the ignition switch.

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While probing around with the volt gauge installed, I think I arced out the 3 o’clock position with the 12 o’clock position, because the gauge is dead now and I smelled a bit of burning. Any thoughts there are appreciated.

Anyhow, I back probed the brown wire in the LIGHT position and fed it 12v, then the alternator began charging. Just need to figure out where I’ve lost voltage to that wire now…

 

[Frankenchevy]

Just as I suspected…

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I fried the PCB

 

[bucket]

Just as I suspected…

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I fried the PCB

That's unfortunate. You can solder in jumper wires though, rather than replacing the printed circuit.

 

[Frankenchevy]

That's unfortunate. You can solder in jumper wires though, rather than replacing the printed circuit.

I may give that a go. Where’s the best place to buy a replacement?

Edit: thinking I’ll get the one from classic industries so I can keep moving on other stuff. Any bad experiences with this product? Looks to be made in the USA.

 

[Jgonick]

pnk/blk wire feeds a lot of things- pull the gage/idle fuse and I bet you lose power on the pnk/blk wire. I have no idea why it would be plugged into the PLFS alternator at F- now if it was an PLIS alternator and it was plugged into I, that would sort of make sense.

Anyhow, I back probed the brown wire in the LIGHT position and fed it 12v, then the alternator began charging. Just need to figure out where I’ve lost voltage to that wire now…

Check for a brn/wht wire plugged into your ignition switch- technically you can use any ignition source (fuse block probably has several ign ports open), just add a bulb or a resistor. see my post above. (or attachment)

 

[Frankenchevy]

pnk/blk wire feeds a lot of things- pull the gage/idle fuse and I bet you lose power on the pnk/blk wire. I have no idea why it would be plugged into the PLFS alternator at F- now if it was an PLIS alternator and it was plugged into I, that would sort of make sense.



Check for a brn/wht wire plugged into your ignition switch- technically you can use any ignition source (fuse block probably has several ign ports open), just add a bulb or a resistor. see my post above. (or attachment)

I have continuity from the brown wire at the alternator side of the harness to this spade:

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[Frankenchevy]

pnk/blk wire feeds a lot of things- pull the gage/idle fuse and I bet you lose power on the pnk/blk wire. I have no idea why it would be plugged into the PLFS alternator at F- now if it was an PLIS alternator and it was plugged into I, that would sort of make sense.



Check for a brn/wht wire plugged into your ignition switch- technically you can use any ignition source (fuse block probably has several ign ports open), just add a bulb or a resistor. see my post above. (or attachment)

Only smallish wire is this tan(?) with white stripe. No continuity to the brown wire at the alternator though…

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I also checked everything at the fuse box just in case, and no continuity there either.

 

[Frankenchevy]

pnk/blk wire feeds a lot of things- pull the gage/idle fuse and I bet you lose power on the pnk/blk wire. I have no idea why it would be plugged into the PLFS alternator at F- now if it was an PLIS alternator and it was plugged into I, that would sort of make sense.



Check for a brn/wht wire plugged into your ignition switch- technically you can use any ignition source (fuse block probably has several ign ports open), just add a bulb or a resistor. see my post above. (or attachment)

Only smallish wire is this tan(?) with white stripe. No continuity to the brown wire at the alternator though…

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[Frankenchevy]

the deeper you dig...

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While probing all the wires around the ignition switch, I noticed that the green and white wires in this harness looked odd. No discoloration, but otherwise look like they got hot at some point.

 

[Jgonick]

Only smallish wire is this tan(?) with white stripe. No continuity to the brown wire at the alternator though…

tan/wht 33 - not it- that is for brake light indicator ground. the brn/wht would have been connected with the orange wire.

Generally-If you do have an idiot light the Brn25 wire runs to the cluster connection (to light that is fed by brn 50 wire) Do you have a brn wire on the connection to your PCB?

Honestly, I'm still confused about the pnk/blk wire at alternator, i went through wire diagrams for 1988 R/Vs and cannot find it like that anywhere.

 

[Jgonick]

While probing all the wires around the ignition switch, I noticed that the green and white wires in this harness looked odd. No discoloration, but otherwise look like they got hot at some point.

Turn signal switch. White wire feed your brake lights (when you step on the brakes)- Dark Grn wire runs to right side brake light. If you are curious on how they work- watch this video -LINK-

 

[Frankenchevy]

tan/wht 33 - not it- that is for brake light indicator ground. the brn/wht would have been connected with the orange wire.

Generally-If you do have an idiot light the Brn25 wire runs to the cluster connection (to light that is fed by pink39 wire) Do you have a brn wire on the connection to your PCB?

Honestly, I'm still confused about the pnk/blk wire at alternator, i went through wire diagrams for 1988 R/Vs and cannot find it like that anywhere.

Neither could I. Everything appears original as I unwrap different sections of harness while investigating. It’s odd. I’ll keep digging.

How important is the resistor in that exciter wire? Is it likely that a presence of voltage absence, a resistor will cause some sort of engine run on event?

I ask because the pink/black wire that is present in the FIELD position of the harness is ignition switched. It would be real easy for me to simply jumper that over to the LIGHT position of the harness as well, but I’m not real clear on what the FIELD wire is doing in this situation.

 

[Jgonick]

I ask because the pink/black wire that is present in the FIELD position of the harness is ignition switched. It would be real easy for me to simply jumper that over to the LIGHT position of the harness as well, but I’m not real clear on what the FIELD wire is doing in this situation.

I personally wouldn't use the pnk/blk wire. -unless we figure out why it is there in the first place. -It supplies a lot of things- All your gauges etc..

The resistance is important- If using the "L" terminal. without it it could cause a short circuit. If your alternator Had "I" instead of "F" it would be easy to plug into "I" without resistant. Really wish you could fine what happens to the brn wire when it comes into the cab.

 

[Frankenchevy]

Really wish you could fine what happens to the brn wire when it comes into the cab.

I probed every dang wire, terminal and fuse block socket and couldn’t find anything. I don’t know if you missed it earlier, but the brown wire has continuity to this spade on the bulkhead junction:

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I personally wouldn't use the pnk/blk wire. -unless we figure out why it is there in the first place. -It supplies a lot of things- All your gauges etc..

I’m wondering if it’s a faded red/black wire. Looks pink to me though and this photo is pretty accurate on screen vs real life on my end.

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The resistance is important- If using the "L" terminal. without it it could cause a short circuit.

I asked Tuff Stuff about just using a ignition switched spot on the fuse panel to power up the LIGHT portion of the harness at the alternator and also about having resistance on the circuit… they said it shouldn’t matter.

Better safe than sorry I guess. I’ll try to find something local at the parts store. Unfortunately there aren’t any Radio Shacks around anymore.

 

[Frankenchevy]

The guy I bought the burb from was kind enough to send me another PCB. This one looks identical except it appears to have a location for a fourth 2” gauge…maybe an idiot light or a clock?

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Both are part number 25044897, but with one being PED-2 and the other PED-4. My original on the top is -4 and the one he sent is -2. The circuits all look like they go to the same locations.

Anyone know of any compatibility issues?