YJ gauges

[RockMonkey]

93 YJ. Anybody ever try to use stock wiring and sensors to run aftermarket gauges? My temp gauge works, oil pressure gauge works, but works backwards. It reads all the way at the top of the scale when the motor is not running, but the power is on, then moves down the higher the pressure gets. I've tried reversing the + and ground wires, but that didn't help at all. Any clues?

When the tach is hooked up the needle moves to zero when it's got power, but when you start the engine it stays at zero. If I hook up the stock gauges they all work fine. Are the stock sending units not compatible with aftermarket gauges?

I have the factory service manuals with all the wiring diagrams to show me which wires run which gauges. Any ideas?

 

[bobdog]

I don't know about YJs but on my CJ the factory tach was wired backwards from the way the Autometer one I replaced it with(It ran off + instead of - or somthing like that). Just wire the tack the way the instructions for the aftermarket tach you have say to. Didn't the presure and temp gages come with there own sensors? I would just use the ones that came with the guages and use the factory wires to keep it clean.

 

[bobdog]

Even if you get the aftermarket guages to work with the stock senders how do you know that they will be calibrated right for the aftermarket guages?

 

[RockMonkey]

Oil pressure-I don't really care about calibration. I just want to know that I have some.
Temperature-I plugged in the stock gauge cluster and let the jeep idle until the temp was stable. then I unplugged that and plugged in my aftermarket gauge, it read the same. Calibration complete.

 

[RockMonkey]

Originally posted by bobdog
I don't know about YJs but on my CJ the factory tach was wired backwards from the way the Autometer one I replaced it with(It ran off + instead of - or somthing like that). Just wire the tack the way the instructions for the aftermarket tach you have say to. Didn't the presure and temp gages come with there own sensors? I would just use the ones that came with the guages and use the factory wires to keep it clean.

What happened on your CJ when the tach was wired wrong? So, you're saying I should try to plug the ground wire from the tach into the hot lead on the wiring harness, and vice-versa?

 

[bobdog]

Originally posted by RockMonkey

What happened on your CJ when the tach was wired wrong? So, you're saying I should try to plug the ground wire from the tach into the hot lead on the wiring harness, and vice-versa?

No the aftermarket tach should have a positive and a ground to power it and a green? signal wire. You just need to find out where to take the signal from. On my CJ the way the factory tach was wired the signal was the opposite polarity of the Autometer If I remember the positive current to the ignition ran through the Tach so that The Jeep would not even run with the tach out of the jeep untill I spliced the two wires together. The afermarket unit hooked to the - side of the coil. Your fuel injected setup is probably completly different I am just saying that you can't assume that the factory guage workes the same. All you have to do is power the guage and hookup the signal wire to the proper trigger.
I looked at the instuctions for my MSD ignition control and a jeep or crysler needs a tach adapter to drive the factory tach while most aftermarket guages do not. This tells me that the factory tachs must be triggered differently.

 

[RockMonkey]

Okay. So I need to get the signal for the tach from somewhere else. Unfotunately I have no instructions (NPS tach), although the tach says on it that the signal wire goes to the alternator. I wonder if there's a spot to hook it up on the alternator. Coil or distributor would make more sense though...

 

[bobdog]

Run the signal wire to the neg side of the coil.

 

[RockMonkey]

A ha! I'll try that one. Thanks.