Road Runner Nest

my car has all new harnesses in it and when redoing componenets like the horn, radio, wiper motor, blower motor i tested them and they worked however know that my car is partially assembled and the dash is back in and new battery in place i dont have any power to radio, blower motor, lights (headlights or dash lights) the horn does have power and the engine will start and run so it does have some things working. please help me with some troubleshooting suggestions. as for gauges the fuel gauge is not hooked up yet so unknown, the car didnt run long enough to confirm temp gauge due to fuel leak. the oil presure gauge went to the far high end with just turning the ket to the acc spot, the amp gauge stayed in center with car off and running.

Sounds like you're missing a ground. I think the radio is grounded by the antenna.Do you have juice at the inputs?

ok i was kindof thinking ground also. i ran out of light so i didnt get to follow through on checking. somebody see if i am thinking of the grounds i need to i have the negative cable to engine and rad support also the forward light harness grounds at same spot on rad support, i remember a ground wire on the driver side of my dash frame from dash harness. also the steering column has a ground wire from column to studs that come off pedal bracket through column support bracket. the antena is installed and pluged into the radio if it does ground through it. the cluster i think has a ground bar on top that should ground to the dash frame when the cluster gets screwed into the frame right? furthermore does anyone know if not having the rear harness and tail lights installed would cause forward light and dash light problems because they are not installed and i remember that there are two grounding screws in the trunk for those, and if it matters i have not put my dimmer switch on the floor yet and it is not plugged up either. thanks for the reply pointing toward grounding gives me some confidence that i might have an easy fix, at least if i am understanding my ground locations as mentioned above.

The Radio is grounded to the dash frame, not the antenna. Blower motor grounds on a wiper motor stud. Forward lighting grounds to the core support. Doesn’t sound like a ground problem to me, get a volt meter out and start troubleshooting voltage supplies, starting at the fuse box. No, the rear body harness will not effect the items in question.

Is this a Rally dash? If so there is what in the book is called a lower reinforcement ground, and if I remember right, there are 2 or 3 grounds that go to the dash frame on the lower left side. Also, there may also be one up above the left kick pal. Do you have a book? If not everybody needs one. Are the door switches installed ? All that stuff works together.

Ok this morning i checked grounds seemed good then i put meter on fuse box found Power on batt side of fuse box all spots found power on acc side in all spots except for 5Amp spot labeled inst. And lmps that lead me to recheck blower motor wipers and radio since they are another fuse. Last week when i posted those didn't work was my stupid i turned the key to first spot but then found another stop just past it and in that position everything works except cluster gauges and lights. Not a fuse i tried to get power at fuse blades no power to that section of fuse block. What next?

Tell us what you mean by first spot on the switch? The switch from off, back is ACC, everything should work. One click forward from off is ACC/run,everything should work, and the engine should run, next is start.

yep first catch as i turn the key is where i was last week when i was checking for power on acc parts. however i noticed today that if i stop the key as soon as i hit that spot no power to accessories but if i continue to turn the key a few more milimeters and it gets to the end of that spot i do get power on the accessories side, however as stated i have no power to the top 5a spot on the fuse block labeled inst/lmps at any point and no headlights no cluster lights no gauge activity except that when the key switch is turned to the acc spot the oil pressure gauge goes past high.

i do have a fsm however i might not be smart enough to use all of it correctly - i have been looking over the wiring diagrams in it and the ones on mymopar.com i am just wondering if a defective headlight switch could be the cause it looks like it gets some power direct and not through the fuse block. now sure if the switch was bad the lights would not work on dash or headlights but would that also be the cause for no power getting to 5amp slot on fuse block? furthermore with meter i did have power at pink wire on dome light plug but not yellows i did not have any power at foot dimmer plug i did have power at brown wire terminal on plug leading to rear harness but no others.

Need to check the 12ga black with white trace wire at the headlight switch for voltage. Receives it voltage via a splice in the dash harness, spliced directly into the alternator side of the ammeter. This is also the power take off circuit for most of the electrical loads of the car while in operation. If unswitched voltage is present, the headlight switch is bad. Yes the 5amp fuse is for the dash illumination lights and receives it power from the headlight switch only when switched on.

72RoadRunnerGTX wrote:Need to check the 12ga black with white trace wire at the headlight switch for voltage. Receives it voltage via a splice in the dash harness, spliced directly into the alternator side of the ammeter. This is also the power take off circuit for most of the electrical loads of the car while in operation. If unswitched voltage is present, the headlight switch is bad. Yes the 5amp fuse is for the dash illumination lights and receives it power from the headlight switch only when switched on.

got it thanks for your help ill check that next

72 Roadrunner /GTX has got you on the right path with the trouble shooting.

The key switch has 5 positions. ACC, LOCK, UNLOCK, RUN, and START in that order. Lock is where you can remove the key, ACC is found by rotating the key back towards you and will supply power to the accessories like the radio. There is no switched power applied in LOCK or UNLOCK positions. Run gives you power to the ignition system, charging system, instruments, heater blower and accessories. Start cuts out all switched power except the starter and ignition.

When you get to the instrument gages, there is a small can on the back of the panel. That converts the 12v from the battery into a pulsing 7 volts for the gages. If one works that tells you that is working. The reason your oil pressure gage swings all the way over is you probably have a sending unit for the dummy light and not the gage. (the sending unit for the dummy light is either open or closed where the sending unit is a resistance from 5-90 ohms ( i think). The fact that the oil gage works tells me the instrument voltage supply is working.

Be patient as these electrical systems were not well thought out. it was the one place mopar kept it's head in the sand and used WAY to many connections. Each being a source of voltage drop and high resistance when corroded. I re-wired mine for better reliability performance and safety- which means the AMP gage no longer works and has been replaced with a volt gage. Which is ok because that circuit is running all the power through the gage. That is damned dangerous now that people are adding more and more electrical goodies. Since your under there, check the 10 ga Black and RED wires to the amp meter. They have to be clean, snug and in good shape ( not cooked with brittle insulation) for the car to even have a chance at working properly.

Ground straps: there should be two . One from the steering column to the dash where the 3 studs are that hold the column up. The second will be where the column meets the floor pan. From the column to the bolt to the floor pan. These ground the column to the body so the key light works and are the path to ground if something like the horn, any of the switches or wiring shorts out.

Ok tested that wire for power and it was present so i installed a new switch with no change i am sure these could be defective when new however i was wondering if there was a different conclusion. Furthermore i put 12 volts to the blade on the switch matching black/white wire location and i only found out put at the blade 2nd row back from front of switch when in on position coincidentally same results with my old switch more suggestions please
Thanks, Kenny

Check B2 at the headlight switch, pink wire, for unswitched voltage. This second headlight switch power feed originates at the Cig lighter fuse and serves the running and dash lights only. Problem there would not affect the main headlights.

72RoadRunnerGTX wrote:Check B2 at the headlight switch, pink wire, for unswitched voltage. This second headlight switch power feed originates at the Cig lighter fuse and serves the running and dash lights only. Problem there would not affect the main headlights.

did it and had power so i went to the marker lights and found power at them and at front marker lights (no bulbs in those locations yet) but still no head lights or dash activity except oil pressure gauge pegged out like before came back under the dash with switch on tested the 5amp fuse location and had a very small amount of power twisted on the dimmer wheel a few times on the new switch and there was the dash lights. however i still had no power at the head lights decided i wanted to test the high beams so i pluged up the foot switch to turn them on and voila head lights sorry to run every one around i thought i had mentioned before that that switch was not connected yet but i didnt and that made the difference all head lights working. furthermore i still think the old switch had a problem because i had tried to get the dash lights on before by twisting that switch with no luck.

also thanks road chicken for your thought on the oil pressure gauge i looked at both styles on the web and checked mine out and it looks just like the one for light not gauge so i have one coming also that made since as to why the thing pegs out when key turned but goes to nothing while running.

thanks for the electrical trouble shooting information 72roadrunnergtx very very helpful, it got my runner running i broke it in today.