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I have a 95 Pontiac Trans Am LT1. Recently replaced the harness and pcm with a new stand alone harness from PSI. My question is, I wired all my gauge sensors into the correct pins on the C220 connector and when I start the engine the only gauge that works is the fuel level. I get nothing out of the tach, oil pressure, temp, and battery volts. Is there a seperate ground that I am missing? Any help would be appreciated. Thanks
 

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Are you sure you consulted a 94 or 95 set of wiring diagrams. Need more information on your conversion. Did you wire gauges to run from the new stand alone pcm.

While newer cars get their info from the computer for gauges, your 95 uses sensors that run directly to instrument cluster.

The tach signal came from the white control wire of icm/coil module, went to pcm then out of pcm on another white control wire to instrument cluster.

If you are in need of original wiring diagrams, we have 94 manual in sticky threads of 4th gen section.

www.bbbind.com will have 95 wiring diagrams to look at or download.
 

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I have a pin out for a 95 pontiac trans am c220 connector. I wired in the water temp (on driver side head) and oil pressure directly from the sensors to the c220 plug that is located under the dash on passenger side. The new standalone harness came with a white tach wire that I also wired into the c220 connector. Im not sure if there is suppose to be a seperate power wire on the cluster or what.
 

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Gauge cluster has 2 power inputs from fuse #9 of in dash fuse box. Connector A cavity 1 and connector A cavity 5. Both are pink wires that are ignition switch on only powered.
 

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What do u guys think of all gauges quit..odometer..speedo..everything...fuses good..cant find a ground issue..bad cluster? 95trans am
 

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Does the engine run? How about other things like turn signals, headlights, wipers, etc?

A pink wire from the electrical part of ignition switch, located under dash attached to steering column, provides key on power to gauges fuse and both injector fuses. So if electrical part of ign sw is not providing power to ip fuse box, then gauge fuse is not getting power.

95 service manual is available at following link. It has wiring diagrams & troubleshooting help. www.mediafire.com/?40mfgeoe4ctti
 

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You need to get your multimeter out. Set it to dc volts. Pull gauge cluster and check the 2 pink wires going into cluster at connector A cavity 1 and A cavity 5. Turn ign on. You should have battery voltage at both wires.

Next check the orange wire at connector A cavity 13. It should have live power all the time.

Next, check the black/white wire at connector B cavity 15. If you place red lead of multimeter on connector A cavity 13 and black lead on B 15, if ground is good you'll read battery voltage.
 
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