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Dash plug wire identification...HELP!!!

J

Jester1

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Need some quick help with dash plug that goes into the printed circuit board. I need to ID the wires at the plug.

I know somebody was just working on this as I saw it on their thread but cant remember who.....

I am installing a few new gauges into my dash and cut the printed circuit board. now my lights have gone all funky, and my gas gauge bottoms out when I turn on the lights. I must have missed a feed through for power or ground when I traced them out. I need to know what color wire does what so I can fix it. I can hard wire most of it to the gauges and bypass the board. What I really need the circuit board for now is dash lights.

86 k 30 454 400 205 no factory gauges just idiot lights. Now I am the idiot that needs to get the lights working.
 
Thanks thats pretty close. Will eventually get tach, new speedo and new fuel gauge installed. Figured out i missed a ground on the printed circuit so made a jumper for now.

Had to button (temp some of) it up so if i die before i finish somebody gets to b!tch about this previous owner's crap wiring.:haha:
 
found these when was looking for the dash plug wiring so i can chase a short in my gas gauge
 
Ok so back on this. Got everything swapped over to new gauges yesterday but can across a fuel gauge problem.

There are 4 wires listed in the pic above for fuel gauge and not sure if i got it right. It says fuel neg, and then fuel ground, and sending unit. The instructions on new gauge just say frame ground the gauge and switch power and sending unit. Not sure i got correct wire hooked for sending unit due to tried one with goofy reading. So thought must have wrong one and hooked up like color for sending unit.

First time I hooked up the listed on plug sending wire i got gauge reading but when testing and reved the motor gauge went past full.

Second time i got rid of common new ground and used the fuel ground the reading went to 3/4 of tank for both tanks then when driving went to empty.

Where i am stumped is this is an 86 k30 454 with saddle tanks and not sure if there is something special/diffrent i need to do with it having 2 sending units.

Any help is appreciated.
 
Forgot to add that gauge was working prior to round one of new gauges then wasn't when i trimmed the printed circuit (was planning new fuel gauge anyway). So i dont suspect the sending units and will double check grounds at tanks.

Where should i be looking for the sending wire to come into one at the switch or gauge. Pics and diagram say wire should be pink. Mine at plug location was dark brown/greyish. First wire i tried. Then fuel neg had 2 wires under plug tan wirh white stripe and ground at plug was black.

Is there a way to test the wire with an ohm meter?
 
Are you using a voltage and continuity tester of some sort to make sure you have the right wires?

Going off improper diagrams or other years is just asking for a headache.

Fuel gauge has only ever used three wires. Power, ground, and sending unit. From what I recall, the sending unit wire could have been many different colors based on year, and unless the vehicle was owned since new by you, can never assume something wasn't changed in the last few decades.
 
Yep i run fluke meters just need to understand how to test for the sending wire. I know that gm used a 90 ohm empty 0 ohm full sender but not sure how to test to make sure i am reading for correct wire. Also as i said there are two tanks and not sure where the two sender wires come together, at dash or switch.

As i understand fuel gauges are nothing more than an ohm tester. Do i test a switched hot to the sending wire or test ground to sending wire. Just need a basic rundown of testing process.
 
Also do they require their specific wires or can you feed the switched hot and ground from a shared set?
 
GM fuel gauges/senders are 0-90 ohms, so you'd test resistance on the sending unit wire.
 
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