I've been searching the thread for a little bit and couldn't quite find what I needed.

I have a '96 bronco without a tach and wanted to put a stock one in. So, I looked for a cluster with a tach and finaly found one. It was from a '93 bronco, but I was told it would work with mine, so i installed it. Everything seemed to work fine at first, but shortly, I noticed my battery was discharging, so I took the truck to Checker and told them about the new clsuter, and had them diagnosed it. They said it was a bad alternator, so I purchased a new alternator and put that in, but that didn't fix the problem. So I went to get my truck diagnosed somewhere else and figured out that wiring from the alternator to the new (older) instrument cluster was the problem. As a temporary solution, we took a wire and connected it to the positive battery end and ran that to the alternator. That works to charge the battery, but I was told I would need to disconnect the wire after I shut off my truck because it would drain the battery.

I was told that If i ground the wire running from the alternator to the cluster right next to the cluster that that might fix the problem, and I was wondering if anyone would know if that is true, or if I would just have to disconnect that too. If anyone knows any way I can get the alternator to charge the battery without having to disconnect any wire so I can keep the tachometer in my truck, that would be greatly appreciated.

 

Whoever told you that the gauge cluster would work is unfortunately misinformed. For a 1996 truck you need a cluster from a 1996 truck.

I forget the boundaries of what's interchangable, but I do remember that the 96's are unique.

 

This is not true, the wire running from the cluster must have 12 Volts more or less for the alternator to charge.

The problem is that the charge wire in 1993 Bronco when into the cluster at C251 Pin #12 and left on C251 Pin #11. In 1996 the charge wire when in at C250 Pin#14 and left on C250 Pin #1.
In both cases the in going wire was a Red wire with a Lt Green Stripe and the out going wire was a LT Green wire with a red stripe.

Here are four diagrams of the plugs so you can see for yourself.

1993 C250
http://i54.photobucket.com/albums/g9...BroncoC250.gif

1993 C251
http://i54.photobucket.com/albums/g9...BroncoC251.gif

1996 C250
http://i54.photobucket.com/albums/g9...BroncoC250.gif

1996 C251
http://i54.photobucket.com/albums/g9...BroncoC251.gif

 

Thanks for the diagrams subford. I figured out what wire running into the cluster was the charge wire, but I coudln't figure out where it was supposed to leave. I told my dad about the problem with the cluster and he offered to buy me a '96 cluster for Christmas so we ended up getting one off ebay. I guess I'll just have an extra cluster around my house, but thanks for the information.

 

physically fitting in the dash doesn't necessarily mean it will work. my dad has a 95 1500, and few years back the motor blew up, i bought him one from salvage yard from a 99 or 00, can't remember and everything bolted up, but dodge changed the wiring harness and instead of flat connectors on all the sensors and injectors, they were round on the new motor, so we ended up putting his old sensors and injectors into the new motor. all it takes is a small change like that to ruin your day, but at least we were able to make it work.