GRAND PRIX Gauge question

[Gpdreamer]

Tech question
Not been on for awhile. I got electrical gauges for my 86 GP, l want to take out the idiot lights and plug in the electrical gauges. Do l plug in the gauges and change the sending units or is there wiring to do? These gauges came from another 86 GP.

 

[Longroof79]

You'll more than likely have to add sending units for oil pressure and water temp. Are you also adding a tach? You'll have to make sure that there's a white tach lead already there. There's a good chance that you may have to add it, and a tach filter.
I'm not positive that the printed circuits are the same for idiot lights and gauges.
I'll have to find my GP wiring diagram.

 

[81cutlass]

I know on a cutlass all the wires are there but have to be repinned in the dash harness where it plugs in. Being a GP has the 2 gauge clusters the wires are probably there but also may be not in the right spots.

The sending units will be different.

 

[Gpdreamer]

You'll more than likely have to add sending units for oil pressure and water temp. Are you also adding a tach? You'll have to make sure that there's a white tach lead already there. There's a good chance that you may have to add it, and a tach filter.
I'm not positive that the printed circuits are the same for idiot lights and gauges.
I'll have to find my GP wiring diagram.

I know on a cutlass all the wires are there but have to be repinned in the dash harness where it plugs in. Being a GP has the 2 gauge clusters the wires are probably there but also may be not in the right spots.

The sending units will be different.

I can change the sending units, the idiot light units both have two terminals and l think the gauge sending units have one, if l was looking at the right part. If just one of the wires work on each. Hate to fry some thing.

 

[Longroof79]

 

[Gpdreamer]

Thanks Longroof79 when l get home l’ll have to pull the cluster out and check the wires. The idiot lights and gauges are in the same position in the clusters. Just have to check the rest.

 

[Longroof79]

Thanks Longroof79 when l get home l’ll have to pull the cluster out and check the wires. The idiot lights and gauges are in the same position in the clusters. Just have to check the rest.

I hope these will be of some help to you. They certainly helped me when I put my GP dash into my Malibu. I had to re-pin the plugs, but in your case I don't think it's necessary.
You're going from Pontiac to Pontiac. I went from Chevy to Pontiac.
Just check to see if there's any difference between the printed circuits. Idiot lights vs. gauges.

Also, like I mentioned earlier. Check to see if there's a white lead for the tach. I think it might be optional with an idiot gauge cluster. You may have to add that...no big deal.
You'll see it indicated in schematic #2.

*The wiring diagrams were courtesy of Doug AKA Old tinsmith. Once again, many thanks to you and your lovely wife.

 

[Wageslave]

I just did the same thing to mine earlier this week on my '85, and here is what I learned:

Cluster - Direct swap, no wires change, just make sure all your backlight bulbs work before you put everything back together

Water temp - just swap to the gauges sensor

Oil pressure - Dummy lights setups use a 2 blade oil pressure switch that goes to a connector that has 3 wires coming out of it. Gauge setups use a large bell shaped oil pressure sender with one terminal on it. I THINK there is a separate oil pressure switch tee'd into the same port that will run your choke heater, but I have never seen one in person. Someone else will have to chime in with confirmation on that. You can either try to recreate the gauges circuit by clipping the sender wire off of the dummy light sender plug and teeing in an original gauges sender on the same port as the dummy light sender. Then take that clipped wire and attach it to the gauges sender.

You can also change to a newer sender that will save you having to tee another sensor into the oil port. I got an oil pressure sensor and pigtail off of a 90's Chevrolet truck that has 3 pins. These have a built in switch that will close when it senses a few pounds of oil pressure. They will wire directly to the 3 wires on the dummy light connector. These senders have a larger thread size than the port on the block, so an adapter will be required but they are easy to come by.

Voltmeter - In theory you shouldn't have to change anything. I am running a newer CS130 style alternator that will require a resistor to be added into the excite circuit, but if you have an original alternator it should be fine as is.

 

[Gpdreamer]

Thanks. Longroof79 for the schematics just looking at that it looks like the second wire goes to ground, the diagram helps.
Thanks. Wageslave your input is going to help a lot, l’m saving these post to go back on when l’m looking at the wires. I’m not using a indash tach (don’t have one) l have a mount tach.

 

[pagrunt]

Voltmeter - In theory you shouldn't have to change anything. I am running a newer CS130 style alternator that will require a resistor to be added into the excite circuit, but if you have an original alternator it should be fine as is.

I didn't think it would be needing a resistor since the volt gauge has an volt light in it.