Wiring and stupid gauges

[hozilla]

https://imgur.com/a/YEQr1iP

I got this truck sight unseen back in November as an early Christmas gift from my wife without the chance to look at it or anything, just woke up to it in my driveway .



I had a Chief in high school and have been looking for a grand Wagoneer for years. No rust, or damage. It came from Texas and is solid as a rock, was supposedly rebuilt 15k miles ago. It runs great, however I have a few issues I would like to fix beyond cosmetics and finishing the interior.

Firstly it had no working gauges but the speedo, I ran a ground from the top bolt of the cluster to the body and I now have a working oil pressure gauge! Nothing else is working however, I bought a temperature gauge from bj's thinking maybe it was the cvr. Still no fuel gauge, there was an after market temperature gauge installed but it doesn't work. Since it's finally warm I have started to poke around and I have found a bunch of wires that, I couldn't really trace and don't know what they are. Tried looking at a wiring diagram but it might as well be in Japanese to me.

the cluster itself is in good condition and I have a second known working cluster where everything works. I have checked the grounds and they seem good, all the lights and everything work but my turn signals, but I am pretty sure I blew a fuse because they worked before. All the pins and everything on both boards are tight and every things clean, i checked all the wires in the circular plug and they are all good, the other plug seems good as well.

Will the cvr work if an aftermarket temp gauge has been installed? Are there any wires directly to the gauge? I know the radio noise suppressor is gone on both boards, could not having the radio noise suppressor thing keep the gauges from working?

Also if anyone can help me identify the wires in the picture that would be very helpful!

I'm going insane trying to figure out this mess.

Cheers!

[inkedmonkey]

What a good present

[MysticRob]

Assuming your profile is correct, you're talking about an 84 Grand Wagoneer, right? Helps to know year, mods, etc...

[babywag]

Will the cvr work if an aftermarket temp gauge has been installed? Are there any wires directly to the gauge? I know the radio noise suppressor is gone on both boards, could not having the radio noise suppressor thing keep the gauges from working?

Couple things...

The radio supressor dealio(or a jumper wire) is needed for the gauges to work. Without it the coolant gauge/CVR doesn't receive ignition power.

The stock gauges depend on a functioning CVR(inside stock coolant temp gauge) to work. Coolant gauge gets ignition power and then CVR drops voltage to gauges(6 volt).

oljeep.com has service manuals, and they have detailed charts to check/diagnose gauge cluster issues.

Follow the power to gauges...
Ignition to coolant gauge, then CVR terminal to other gauges.

[hozilla]

Assuming your profile is correct, you're talking about an 84 Grand Wagoneer, right? Helps to know year, mods, etc...

Yes it is an 84, sorry about that.

[hozilla]

Couple things...

The radio supressor dealio(or a jumper wire) is needed for the gauges to work. Without it the coolant gauge/CVR doesn't receive ignition power.

The stock gauges depend on a functioning CVR(inside stock coolant temp gauge) to work. Coolant gauge gets ignition power and then CVR drops voltage to gauges(6 volt).

oljeep.com has service manuals, and they have detailed charts to check/diagnose gauge cluster issues.

Follow the power to gauges...
Ignition to coolant gauge, then CVR terminal to other gauges.

Thanks babywag, I wonder why my oil gauge works without the jumper then if it is needed to run the gauges.



Any idea where I can read how to jump the radio suppressor? I have checked the board and haven't really found anything.


Cheers!

[tgreese]

Thanks babywag, I wonder why my oil gauge works without the jumper then if it is needed to run the gauges.



Any idea where I can read how to jump the radio suppressor? I have checked the board and haven't really found anything.


Cheers!

You can clip the two posts together and see if your gauges work then. Improvise something to wire them together. You won't have the radio noise suppression of the actual part, but the gauges will work if nothing else is wrong.

The only source for a replacement part will be a junked instrument cluster from a parts car or wreck. Try the WTB (want to buy) forum here.

You are correct. From the '84 wiring diagram at the Tom Collins site, the OP gauge should not work if the CVR is not working. The '84 diagram pages on that site do not connect very well. Suggest you buy the TSM and get printed diagrams, or perhaps look at earlier years for a better idea of the wiring.

[hozilla]

You can clip the two posts together and see if your gauges work then. Improvise something to wire them together. You won't have the radio noise suppression of the actual part, but the gauges will work if nothing else is wrong.

The only source for a replacement part will be a junked instrument cluster from a parts car or wreck. Try the WTB (want to buy) forum here.

I will try that, I appreciate the help. I am a complete newbie to all of this so the forums have been a life saver.

[hozilla]

Update: Jumped the radio noise suppressor still no fuel or temp gauges, are there any wires or anything going to the temp/cvr that I am missing maybe? The wiring in this truck is a birds nest of sadness.

[tgreese]

I think your only option is to trace it through, circuit by circuit. Not much can be done remotely. You need the wiring diagram, a multimeter or test light, and the car in front of you.

In the past I have photocopied the wiring diagram, blown it up to twice its original size and taped all the sheets together. Then I traced each circuit with my multimeter. I used colored pencils to highlight each circuit in its wire color as I traced it.

You have to take it circuit by circuit and check it out.

The CVR is an on-off voltage regulator. It turns on and off at about one second intervals, and the average voltage is about 5-6 volts. The display of a digital meter will not follow this closely, but you should be able to see this with your meter.

[hozilla]

I think your only option is to trace it through, circuit by circuit. Not much can be done remotely. You need the wiring diagram, a multimeter or test light, and the car in front of you.

In the past I have photocopied the wiring diagram, blown it up to twice its original size and taped all the sheets together. Then I traced each circuit with my multimeter. I used colored pencils to highlight each circuit in its wire color as I traced it.

You have to take it circuit by circuit and check it out.

The CVR is an on-off voltage regulator. It turns on and off at about one second intervals, and the average voltage is about 5-6 volts. The display of a digital meter will not follow this closely, but you should be able to see this with your meter.

are there any wires that wire up to the gauge itsself?

[tgreese]

Depends on which gauge.

The temp gauge has 4 connections:
- to the temp sensor in the engine block
- battery power (+) in
- CVR power (+) out
- ground (-) through the case of the gauge

The cluster must be grounded to the dash. Normally this grounds through the attaching screws. If you pull the cluster out, you must add a ground wire from the cluster to the dash, or no CVR action (The CVR will stay on all the time, which will cook your gauges).

((( Ok, briefly looking at the manual, only the CJ requires a wire from the cluster to ground, if both plugs are plugged in. The ground is pin 4, as mentioned above, and is part of the smaller plug. You do not need an additional ground for the CVR to work. )))

The other two gauges (OP, fuel) have two: CVR power (+) in and connection to their sensor.

This is discussed in the TSM and shown in the wiring diagram. If you're going to work on your own car, you need to be able to use these resources.

[tgreese]

Looking at my '82 TSM, there are step by step procedures for diagnosis and test of gauge problems. I presume the one for your year has this too:

https://www.bjsoffroad.com/1984-87-Jeep-Grand-Wagoneer-and-J-Truck-Factory-Service-Manual_p_1056.html

BJs will give you a modest discount as a member of this forum.

There is most of an '82 TSM here https://oljeep.com/edge_parts_man.html Read section 1L, Engine Instrumentation.

[backroadin']

Another option is to get a 3 gauge afftermarket set and wire it up all new... i.e. not with existing wiring. As for the fuel gauge, check/clean the ground on the sending unit cover and test continuity between the wires coming from the sending unit and the gauge. Nothing wrong with runing new wires if you have to or running an aftermarket gauge here too. All my gauges except the speedo are aftermarket - it's almost a given that these old rigs have non-working gauges!! As to an aftermarket fuel gauge if you ever go that route - make sure you know the resistance range of the stock sending unit and if empty or full is low resistance, and make sure you get a gauge that matches. They are not all the same.