MVPaquatics Posted September 17, 2012 Share Posted September 17, 2012 I only ask because I got a few pm's from other people with similar trucks when I showed pics of it in the cars thread 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 PN 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? I highly doubt the abbreviated haha Quote Link to comment Share on other sites More sharing options...
peligro Posted September 17, 2012 Share Posted September 17, 2012 Well inside the fuse box where the fuses go are wires that complete that circut. The fuse is there to blow first if it surges. When my Honda 86 did that. I opened the fuse box, took out the fuse holders and found my problem one of the wire connects were broken off. I just sawdered it back. Eventually I replaced the whole fuse box. But that's just what I did. And found HTC EVO Quote Link to comment Share on other sites More sharing options...
Islandoftiki Posted September 17, 2012 Share Posted September 17, 2012 Does it have a dash light rheostat? Did you try messing with that? Sometimes they get a bad connection and have to be operated back and forth for a little while to get them going again. Quote Link to comment Share on other sites More sharing options...
racefan Posted September 17, 2012 Share Posted September 17, 2012 I do not even pretend to know about wiring, however here's a link to the best truck board you will ever find for Chevy trucks. http://67-72chevytrucks.com/ They will help you with pretty much any problem & not have have all the crap that goes with some boards. I'm a moderator over there. It was a great resource when my son & I did his 72 LWB. Quote Link to comment Share on other sites More sharing options...
Islandoftiki Posted September 17, 2012 Share Posted September 17, 2012 We only have wiring diagrams for Swedish cars here at work, but if you have a wiring diagram, I could probably figure it out in a matter of minutes. Computer systems and electrical are my specialty. Quote Link to comment Share on other sites More sharing options...
MVPaquatics Posted September 17, 2012 Author Share Posted September 17, 2012 Does it have a dash light rheostat? Did you try messing with that? Sometimes they get a bad connection and have to be operated back and forth for a little while to get them going again. I think i have it narrowed down to the headlight switch. Power goes into switch, splits into headslight, park lights dome and cluster/instrument. Then it goes to fuse panel then to repsective lights. Everything works except cluster/instrument gauge lights. It must be the switch because all other wires were ohmed out and test ok. Just no power between switch and fuse box for cluster lights. Any way to test the switch? Someone said something about B+ but i am unfamiliar with that setting, or is it a result? I have a buddy asking questions on the 67-72 chevy truck forum! Thanks racefan! Quote Link to comment Share on other sites More sharing options...
MVPaquatics Posted September 17, 2012 Author Share Posted September 17, 2012 Does it have a dash light rheostat? Did you try messing with that? Sometimes they get a bad connection and have to be operated back and forth for a little while to get them going again. By rheostat do you mean mutifunction? Its pull halfway for park, pull all the way for headlights twist to get cluster brighter (part that doesnt wprk)and twist and click for dome light I think i have it narrowed down to the headlight switch. Power goes into switch, splits into headslight, park lights dome and cluster/instrument. Then it goes to fuse panel then to repsective lights. Everything works except cluster/instrument gauge lights. It must be the switch because all other wires were ohmed out and test ok. Just no power between switch and fuse box for cluster lights. Any way to test the switch? Someone said something about B+ but i am unfamiliar with that setting, or is it a result? I have a buddy asking questions on the 67-72 chevy truck forum! Thanks racefan! Apprecaite everyones help Quote Link to comment Share on other sites More sharing options...
racefan Posted September 17, 2012 Share Posted September 17, 2012 We only have wiring diagrams for Swedish cars here at work' date=' but if you have a wiring diagram, I could probably figure it out in a matter of minutes. Computer systems and electrical are my specialty.[/quote'] Darn...I wish I was closer. Have a 67-72 shop manual. Quote Link to comment Share on other sites More sharing options...
Barelycuda Posted September 17, 2012 Share Posted September 17, 2012 IF you have power to the switch but not out of the switch to the dash lights you can put a jumper wire across the switch to test the circuit. If the lights still don't light up then your problem is elsewhere but if they light up then the switch is the problem. Quote Link to comment Share on other sites More sharing options...
Islandoftiki Posted September 17, 2012 Share Posted September 17, 2012 IF you have power to the switch but not out of the switch to the dash lights you can put a jumper wire across the switch to test the circuit. If the lights still don't light up then your problem is elsewhere but if they light up then the switch is the problem. Yeah, this. Almost every car has a dimmer for the dash lights. Older cars like that usually have a dimmer that's a sweep arm that contacts a metal resistor spring. They get corrosion between the sweep arm and the spring. I'm a European car guy, but I remember old american cars having the dash lights dim by turning the headlight switch, but I honestly have no idea on your car as I've never even touched one. My co-worker also guessed that it would be a turn the headlight switch knob kinda deal. Quote Link to comment Share on other sites More sharing options...
Islandoftiki Posted September 17, 2012 Share Posted September 17, 2012 I guess regardless, it wouldn't hurt to try to get some electrical contact cleaner into the switch if that's possible. Quote Link to comment Share on other sites More sharing options...
pnkrcklives Posted September 18, 2012 Share Posted September 18, 2012 Yes the headlight switch is also the rheostat for the dash dimming(rotate knob). Very common problem on these. Like John Said try some crc electronic cleaner in there and maybe a little stabilant 22 if you can find some. Try bypassing the rheostat and see if the lights work. If you have a power probe it is super easy to do. I think I have a test switch lying in my parts somewhere at the house. But my money is on the switch. Quote Link to comment Share on other sites More sharing options...
pnkrcklives Posted September 18, 2012 Share Posted September 18, 2012 autozone and napa both show them in stock for less than 20 bucks Autozone part #SW141 Napa Part #MPE HL6554SB Quote Link to comment Share on other sites More sharing options...
MVPaquatics Posted September 18, 2012 Author Share Posted September 18, 2012 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. Crazy good help, and from a fish forum no less! Thanks again Quote Link to comment Share on other sites More sharing options...
MVPaquatics Posted September 18, 2012 Author Share Posted September 18, 2012 41 years young and still turning heads everywhere she goes. She said thanks for checking a little bit off her to-do list lol Quote Link to comment Share on other sites More sharing options...
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