[PDC]

Looking at swapping the gauge cluster in my 73 Trans Am. It currently has functional 6k tach and 100 mph speedo which clearly is not correct for the 73 car. But every gauge in the cluster works: tach, speedo, temp and oil pressure.

I have done quite a bit of research and see that the contacts on the printed circuit boards ‘appear’ to be consistent for 1970, and then 1974-76 cars. The circuit board contact pattern for 1971, 72, and 73 cars is all the same - but it is different than the 70, 74-76.

My question is this - will the harmonica in the dash harness for a 73 Trans Am work with any 70-76 gauge cluster, or if I have (for example) a 74 gauge cluster, will I need an entirely different dash harness with different harmonica clip?

Because all of the gauges in this technically incorrect 100 mph 6k tach cluster work properly in my 73 car, I wonder if the dash harness clip will power up pretty much any 2nd gen cluster, or if the PO necessarily changed out the dash harness when swapping in this incorrect cluster.

Hope this question makes sense.

Thank you.

[PDC]

Looks like I posted this in the wrong forum - I have re-posted in the electrical sub-forum is the Moderator would like to delete this thread. My apologies.

[78w72]

Originally Posted by PDC

Looking at swapping the gauge cluster in my 73 Trans Am. It currently has functional 6k tach and 100 mph speedo which clearly is not correct for the 73 car. But every gauge in the cluster works: tach, speedo, temp and oil pressure.

I have done quite a bit of research and see that the contacts on the printed circuit boards ‘appear’ to be consistent for 1970, and then 1974-76 cars. The circuit board contact pattern for 1971, 72, and 73 cars is all the same - but it is different than the 70, 74-76.

My question is this - will the harmonica in the dash harness for a 73 Trans Am work with any 70-76 gauge cluster, or if I have (for example) a 74 gauge cluster, will I need an entirely different dash harness with different harmonica clip?

Because all of the gauges in this technically incorrect 100 mph 6k tach cluster work properly in my 73 car, I wonder if the dash harness clip will power up pretty much any 2nd gen cluster, or if the PO necessarily changed out the dash harness when swapping in this incorrect cluster.

Hope this question makes sense.

Thank you.

if the prev owner didnt swap the wire harness & cluster to a later style 6k/100mph with the bigger harmonica connector, then chances are they just swapped the tach & speedo by themselves into the 73 gauge cluster using the smaller connector. but you will need to pull the gauge or look up behind it to verify what connector/cluster it has.

to answer your question, if the 73 has the earlier smaller connector it wont work for the later 74+ gauges as they use the bigger connector. on my base model 72 firebird i swapped in a 74 wire harness & gauge cluster since it uses the same block at the firewall it was easy to swap, that might be an option on your 73 if you plan to swap the harness & cluster.

however, the easier way to do this if the car still has the smaller connector/harness & cluster, is to just swap out the 6k/100mph for a 8k/160mph since the speedo & tach are controlled independently of the printed circuit/harmonica connector. tach is controlled by a standalone wire & speedo is obviously ran by the cable. the only thing that might not work right is the brake or bright indicator in the speedo since they are fed by the printed circuit bulbs.

once the cluster is pulled, the speedo & tach are easy to swap with just a few bolts/nuts on the back side. they repro both gauges new or can find them used for much cheaper. i have a bunch of 8k & 160 gauges if you need them.

[Skip Fix]

I swapped a few pins in my plain jane 79 Camaro idiot light harness to use a Z28 cluster. But then repinned to use after market gauges.

Most wiring diagrams show you colors and pin position in the harness plugs.