Help: no power to panel lights on fuse box?

[Mbeef61]

I have a 71 chevy stepside. Everything was working a year ago. Sat for a year. Brought it back out. Everything is great but the instrument cluster lights dont work. All other lights work. Signals work both outside and inside indicators. Gauge lights do not. Red brake light works upon startup. Just not the gas gauge, speedo etc. Tried fuses, no success.

Multimetered the fuses by putting negative to chassis ground and positive to fuse bottoms, all but the PNL lights (top right) fuse shows around 12.5 volts with truck off. This is correct? Also ohmed out fuse and wires from instrument cluster to fuse box and got a good signal (that indicates no short correct?).

I am wondering why or how I could be getting no power to one spot on fuse box? Any ideas?

Also, fuse box says 3A in some spots, like PNL lights...that is 3 amps fuse correct? PO had a 30 amp in one of them, but it wasnt one being used. Probably just holding an extra...but 3A requires a 3amp fuse right?
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[Mbeef61]

Also an another question but not as important. PO dismantled the license plate lights...how do they figure into the mix? What circuit are they in with?

Please dont hesitate to any any or all of the questions. Any info is helpful! Thanks!
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[SS Tim]

Sounds like you don't have a wiring diagram. The IP lamps fuse is powered from the headlamp switch. Power goes into the switch and is then routed to the fuse block to run through the fuse. A 16ga Dark Green runs to the block and a 20 ga Gray runs to the cluster connector and heater lamp bulb. With park or headlamps "on" you should see "B+" at the fuse (both sides). Thinking that the switch itself is probably the problem. But checking and not guessing makes for cost effective repairs.

[Mbeef61]

Correct, no official diagram. Just ones i find on here and tracing wires/pathways.

I hadnt check that pathway, thanks for the insight!

I ohmed the green wire from switch to fuse box and got a good signal but no juice. Bad switch?

I am unfamiliar with B+ setting. I have a digital fluke meter. How do I access that setting and what am i looking for as far as a reading?

PNL lights is a 3A fuse right?

[Mbeef61]

Found a diagram here http://67-72chevytrucks.com/vboard/s....php?p=5190913
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[SS Tim]

These are generic schematics but close.
http://67-72chevytrucks.com/vboard/s...d.php?t=185856

[Mbeef61]

Sorry i may have edited while you were posting...found a diagram. Questions about testing

I ohmed the green wire from switch to fuse box and got a good signal but no juice.Bad switch?

I am unfamiliar with B+ setting. I have a digital fluke meter. How do I access that setting and what am i looking for as far as a reading?

PNL lights is a 3A fuse right?
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[SS Tim]

If you don't have them, there are several reference materials every owner should have. Reprints are fine both Disc and paper have their place as well.
Model Year Specific

Owners Manual
Factory Chassis Service Manual
Factory Chassis Overhaul Manual

Sales Brochure is also nice for those little what was what questions.

As an example here is the fuse info. from a '68 Owners Manual

[SS Tim]

Originally Posted by Mbeef61

Sorry i may have edited while you were posting...found a diagram. Questions about testing

I ohmed the green wire from switch to fuse box and got a good signal but no juice.Bad switch?

I am unfamiliar with B+ setting. I have a digital fluke meter. How do I access that setting and what am i looking for as far as a reading?

PNL lights is a 3A fuse right?
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If the wire is good check for voltage at the fuse terminals and the connector at the switch. The switch is probably bad or the dimmer rheostat could just be corroded up. Try running the dimmer up and down a couple of times to clean the contacts.

B+ is just an expression for battery voltage. Meaning the reading should be very very close to the actual battery voltage. In this case it would be measured with the DC volts position on your meter.

Cluster Fuse is 3A on all the '67-72 light trucks I believe.

[Mbeef61]

It turned out to be a bad switch. I ohm/volt tested it and that was it. New one at baxters was $15. Did the 192 to 168 bulb switch while i was in there, as well as replaced all rusty fuses. Also fixed the signal indicators that were not working all the time.

Next up is the temp gauge and battery indicator, as well as calibarate the speedo, license plate and backup lights. I will research those before i ask questions and start new threads if needed.

Again thanks for the help/pointers and links. It really made it MUCH faster than without. Hopefully someone else can use this and learn something
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[Mbeef61]

41 years young and still turning heads everywhere she goes. She said thanks for checking a little bit off her to-do list lol


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[SS Tim]

Glad that went smooth. Down here a year and non-functional electrics are generally rodent related.

Hope your other planned projects go as well. The schematics and fuse chart will be very helpful for the gages and tail lights.

Good Luck, Welcome to the Board and don't be afraid to ask questions. I really feel for the guys who throw a bunch of parts and time at a problem they didn't understand for lack of asking a question.

[VetteVet]

This may be of some help to you. The 2nd diagram on the top of the list shows the green and gray wires on the fuse box. The 12th wire from the bottom on the lower right is the feed wire from the headlight and it feeds the gray wire through the fuse.
The 1st diagram shows the gray wire going to the dash cluster . It also shows the tail light harness going to the rear of the truck and the license plate light ties into the brown tail light wires.

http://www.2heeldrive.com/Chevrolet/Wiring_Diagrams/

[tsali39]

Thanks VetteVet, I am still struggling with this same problem. I did replace the light switch, fuses and all bulbs. I have no cabin light working also. I do not even see a wire heading in that direction. Could this be the loop that is causing the problem? I also have no wire going to the heater bulb.

[VetteVet]

Originally Posted by tsali39

Thanks VetteVet, I am still struggling with this same problem. I did replace the light switch, fuses and all bulbs. I have no cabin light working also. I do not even see a wire heading in that direction. Could this be the loop that is causing the problem? I also have no wire going to the heater bulb.

The diagrams show the fuse panel has a full time hot red wire feeding the orange wires that feed the stop light switch, the dome lamp and the head light switch. You must be missing the dome light feed and the head light feed wires.

The orange wire that goes to the headlight switch feeds the dash light rheostat which feeds the green wire back to the fuse panel. The green wire feeds the gray dash light wire through the cluster plug and there should be a double gray wire on the cluster plug, one from the fuse panel and the other goes to the heater bulb.

below is the diagram showing the red wire coming into the fuse panel and the orange wires off of the fuse.Ignore the arrows, they are for another problem.

The fuse panel is in the lower right center.



This is the feed to the head light switch. You can see the orange wire and the green wire on the switch.



This is the other orange wire that runs to the dome light.



If you look at the two cluster connections on the middle diagram you can see the double gray wires for the dash and the heater lights. They are pinned differently on the gauge cluster and the idiot light clusters.

[slikside]

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