Rewiring for gauges, question regarding GMCPaul instructions

[-sean-]

I'm in the middle of my rewire for changing over from idiot lights to gauges using the tips from GMC Pauls web site (http://www.gmcpauls.com/Tech%20Tips1.htm). I have couple of questions.

First off, why does the cluster power source have to come all the way from the junction box (which is always "hot") on the pass side front fender near the battery? Couldn't this just come from the fuse box which actually has a spot called "cluster feed"?

Second, the wire that feeds the "battery" gauge is supposed to come from the red (+) wire that runs between the alternator and the regulator. Why cant the old wire for the charging idiot light be used for this? And this wire is "hot" all of the time which would cause a constant reading on the gauge and a drain on the battery correct?

Thanks guys

BTW, just out of curiosity, how many folks have actually used the GMCPaul instructions and how did it work out for you?

[MARKDTN]

When I do anything like this, I take the old cluster and the new one and then diagram what each wire does. Then swap the plug wiring from old to new configuration. You also need a good diagram on how the ammeter is wired. GM is not as hard to change over as Ford as I recall. I can't answer your specific questions, but there should be at least 1 ignition hot from the fuse box.

[-sean-]

Originally Posted by MARKDTN

but there should be at least 1 ignition hot from the fuse box.

This is one of my concerns.
The "hot" coming from the junction box is constant which will have the gauge cluster receiving power all of the time, this doesn't sound right to me.

Also, there is an open un-fused spot on the fuse block itself called cluster feed. (?)

[VetteVet]

The cluster power comes from the fuse panel via a pink wire from the cluster feed fuse. The fuse is fed by a different pink wire that comes from the key switch and this wire gets it's power from the battery junction on the right fender.

Here is the diagram of the pink wire from the key switch to the fuse panel. The red power from the battery junction is on the very top of the diagram and the pink wire is just 5 wires below it. Follow the pink wire down to the fuse panel and you'll see the pink wire next to it that goes to the cluster plug.


Here is the engine side of the ammeter wiring showing the junctions and the wires to the ammeter with a 4 amp fuse in each wire and where the wires go. You will have to run these wires and put the fuses in to protect the ammeter.

Here is another view with the fuses and the wires. The red wire on the left that is labeled SHUNT is the connection between the battery and the alternator that the ammeter uses to read a voltage differential between the battery and the alternator to indicate a charge or discharge condition on the system.


No you can't use the wire to the idiot light because it is the wire that excites or Turns on the voltage regulator so the regulator will tell the alternator how much amperage to put out to charge the battery and run the accessories. This wire is not used anyway on the gauge clusters. It is replaced by a brown/white stripe wire from the key switch that is a resistance wire to turn on the regulator in place of the idiot light. It should be in the first diagram at the top and runs down the left side to the inside of the firewall block. On the other side of the block it becomes a 116 gage brown wire that runs to the external voltage regulator. If you have converted to an internally regulated alternator then it will run to terminal one on the alternator body.