Pulsating wire under the dash

Pulsating wire under the dash


Senior Jeeper
1979 Jeep CJ5 with '72 304 V8, MC2100carb,T150 trans, AMC20 rear diff with locker, Dana 30 front diff, Dana 20 Tr Case, Procomp Springs, Gabriel Ultra shocks.
Todays project been messing around getting the lights and gauges to work properly on my CJ5. I replaced the oil pressure gauge and the needle on the gauge is pulsating. I don't mean slightly vibrating, as is common with that gauge, but it is pulsating zero to max like a turn signal. I disconnected the gauge and checked the red wire with a light gauge and it is pulsating. It shines very bright every second. I swapped the hot volt gauge wire on to the oil gauge and the gauge worked fine. So, I am guessing that the PO had the wrong wire hooked up to the oil gauge but there is no other wire available. He also rewired the ignition to be in the dash, so I am wondering if he simply cut it out. I am going to splice off the volt meter wire to the oil gauge which should work fine. The only other things that do not work at this point is the fuel gauge and the clock. I think the fuel gauge issue is a poorly installed fuel sending unit because it registers when the tank is full but not as it goes down. The clock is just trashed.

My question is what would a red pulsating wire be for?
Further investigation shows, when using a light tester, that it comes on when the ignition is turned on. It stays bright and constant for a second or two before it starts flashing.
Further investigation shows, when using a light tester, that it comes on when the ignition is turned on. It stays bright and constant for a second or two before it starts flashing.

odd but ok
Is there a key switch on the column?
is the turn signal lever going into the knob or a "box" mounted on the side?
now the hazard button.....does it respond mechanically and electronically?
the dash mounted ignition.....have you traced the wires?
is it like the pic below or did they splice from ignition on lower column? and could you post a pic of the dash and column ?
this has me wondering about whats not pulsating or not working
The ignition was stripped out of the column and an aftermarket ignition was installed on the dash. Its a red wire exiting the wiring harness behind the oil and voltmeter cut outs. It has what appears to be a factory plug that would fit on to a gauge stud. It is not affected by the flashers or the turn signals and there is no "clicking" noise to account for it. It basically flashes the way the temp sensor wire flashes at the engine, so I wonder if it is some sort of sensor.
I'm getting closer. I pulled the fuse labeled "BU/Seat Belt" and it stopped flashing. When I say flashing, I mean the the light meter. So, I can only assume that there is and/or was a seat belt light or chime? I assume that I can let this hang and not worry about it?
I figured it out. Spent a couple hours on my back sprawled across the seats upside down with a few occasional trips back to the house to look at diagrams and what not on the internet.

The PO had plugged an unknown, as I type, red wire in to the A terminal, or jumper, of the temperature sensor. The sensor was causing the pulsating wire.

As yet, I do not know what the two loose red wires are that I am left with which are obviously spliced somehow. I'm going to work my way through the fuse box and see if I can find what they are supposed to power. Now the only thing that doesn't work, which did before the brake job, is the brake light for the parking brake. Maybe there is a link between these wires. I'm also missing the wire for the cigarette lighter, so that might play a role too.
FWIW I was reading a trouble shooting guide for the CH dash the other day and it stated one of the sensors will cause a flashing and that thats normal (I think).

Here it is..
Basic Troubleshooting for CJ gauges

May want to read through it.

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