Sorry for another wiring Question

[phillipmhampton]

just installed wiring harness after restoration of 74. having trouble with dash illum lights and gauges. gauges don't do anything. ivr reading variable voltage on back. fuse block has power to all fuses except dash lights 2 amp fuse. also have tried to different headlight switches in every position.

A. Are these independent issues?

B. voltage to gauges is <1 to 5 volts. shouldn't the gauges at least flutter? checked voltage by grounding to back of gauge/spedo housing so i think ground is good.

C. there is phantom blue and red wire to the back of ignition switch (post not plug). can't seem to find it on wiring diagrams. any ideas?

Thanks in advance for any answers!

 

[Blue Bastard]

hmm. blue/red is the guage lighting. That is your proplem. Not sure what to advise to correct though. I "THINK" it picks power up at the ignition.

Make sure the contacts are clean on the fuse block as that tends to Be a issue asuming you are useing a stock harness and fuse block.

 

[phillipmhampton]

so close!

so resolved a couple issues! instrument lights weren't working because bad headlight switch ( the third one i tried worked). headlights because bad dimmer switch lol. now all i gotta do is fix this gauge problem. gauges are completely dead. ivr has variable voltage 1-5. is there some sort of ground I'm missing? pretty sure cluster is good ground and dash is as well. completely stumped here. thanks for that last reply and thanks in advance for any future ones!

 

[Blue Bastard]

You Can try this as a test. take any one of the lead wires to the senders and ground it out to any part of the truck. That should make the needle peg. if it doesnt then it is a IVR problem i would think.

here is a wiring diagram if you need referance.

 

[phillipmhampton]

Just did the test you recommended. and the oil pressure gauge pegged out. this is driving me crazy lol. if i measure voltage from ivr and use back of cluster as a ground i assume this means it has a good ground? does engine need ground to body/frame? that might be a stupid question!

 

[Viperwolf1]

Just did the test you recommended. and the oil pressure gauge pegged out. this is driving me crazy lol. if i measure voltage from ivr and use back of cluster as a ground i assume this means it has a good ground? does engine need ground to body/frame? that might be a stupid question!

Body needs a good ground to the engine. Usually the clusters are not grounded well. Yours is if you see the varying voltage out of the IVR.

Your oil pressure gauge is working. Sender or sender wire may not be. Look for the varying voltage at the sender wire. Same for fuel and temp.