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Discussion Starter #1
Any help would be appreciated! I have a 1985 Mustang GT that I have rebuilt from the ground up, but recently I decided to change out the original gauge cluster and put in a cluster that had a 140 mph speedometer. the replacement cluster was in excellent condition but it was out of a 1984 turbo coup. There is a turbo gauge in place of the ammeter, and the printed circuit looks identical to the one I took out. However, I have no lights in the cluster even after putting in all new bulbs. Has anyone ever done a switch like this? Can anyone give me the pin wire identification from both of the plugs that go into the back of the cluster.
Thanks, and have a great summer.
 

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you need to source the wiring diagram for the donor car and match it to yours

or trace out each circuit, you may to repin the connectors
 

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Discussion Starter #3
Thanks indy 2000. I got this piece on line so I don't know if there is a diagram of the pin location. (84 Mustang turbo) I haven't found one on line. I checked the pins last night with my meter and found 12+ volts in several locations but it's not easy getting under the dash to trace the wires even with the driver's side seat out, but thanks for your response.
 

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Discussion Starter #5
Another mystery encountered. I replaced my fuel system to feed my Dart block based 427. The tank now contains an aftermarket pickup with AN10 line to feed the engine and 6AN return. The pickup has been verified as 75-10 ohm. which is compatible with my 73-10 in dash gauge. The fuel is pushed by a Holley in-tank 340 lph electric fuel pump to a Sniper EFI system. All the wiring has been checked and everything is working properly except when I top off the tank the in dash gauge only reads half full. I bought an Auto-gauge fuel gauge and wired that in but nothing has changed, they both read the same, one half tank when the tank is full and as I burn off fuel they both go down accordingly but I have no idea how much fuel is left in the tank. Has anyone had the same problem, and what is the potential fix. Thanks!
 

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Discussion Starter #7
I checked everything in the cluster as well as the pin connectors and everything is as it should be. I have quick connects in the back so I checked there too. If I leave the ground wire connected and check the hot lead the gauge goes to full so I don't think it's a gauge problem. So, hopefully someone has a better idea or I get lucky and find the problem myself. Thanks.
 

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Discussion Starter #9
This is going to sound crazy!!! I went to my connections in the rear of the car and with the ignition on I took a jumper wire and hooked it to the hot lead directly from the tank, and used the other end of the jumper to ground. The Autometer gauge went right to full but I know the tank is not full. I then took the jumper wire and hooked it to the other connector and then to ground. The Autometer gauge never moved but the in dash gauge went to full. I really stink at this, and hope I'm not too much of a bother.
Thanks for the help.
 

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i asked for a short and open

no jumper needed

take the two wires for the sender at the tank

disconnect them, look at the gauge, what does it do?

then take the two wire, and touch them together, what does the gauge do?
 

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Discussion Starter #11
Reference step 1) I disconnected the two wires and the in-dash gauge went to empty. The second Auto meter gauge I wired in the other day went to 1/4 tank.
Step 2) I touched the opposing two wires together and the in-dash gauge stayed empty but the Auto meter gauge immediately jumped to full.
I hope this helps a little if not I'll have to find a really long dip stick.
 

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Discussion Starter #13
The in-dash gauge wasn't working properly so I added the new Auto meter gauge. I'm thinking I'll just disconnect the in-dash gauge and go strictly with the Auto meter gauge in an independent location.
 

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I am sure the gauges have different sender requirements

The open and short circuit test, just confirms wiring
 
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