I had the alternator tested and it passed but the bearings were shot so they replaced it and checked everything else while it was apart. nothing but the bearings needed replacing. I installed the alternator and the RPM gauge still doesnt work. Another 97 DI that I recently worked on has allowed me to "borrow" her alternator to test this possible fix. I'll update this Sunday after I swap them.

 

Make sure all your connections to the alternator are clean and tight. Use dielectric grease.

 

just a few thoughts since my name was thrown into the mix, bad grounds appear to be notorious in these trucks! this may be the reason there are so many complaints about electrical problems, or it could just be all the extra electronics (we may never know, just kidding) anyways I would clean (unbolt, scratch off the paint with a wire brush, and rebolt them down) every ground you can find, may not fix your problem but if it does it is cheaper than replacing fuel sending unit or the pump! always start with the small possibilities first, nothing like spending a bunch of money and doing a bunch of work to find out your battery cables are corroded or loose,you have a bad ground, a blown fuse, or something small like that. Best advice I can give.

after that if your problem is still there you could always use a multimeter to read the wire (look up the schematics in the rave manual to see which one) and see if the unit is actually sending the right signals right from the sending unit. like I said eliminate all other possibilities first.

 

check the fuse for the MFU (multi function unit) this is interconnected with a lot of the trucks electrical systems, the owners manual even says to check it when any other electrical problems occur, "In the event of failure of any electrical system component,always check fuses 12 and 13 in addition to the appropriate component fuse." I also read about an engine speed sensor , I think, in thee haynes manual. you might want to look into that.

 

UPDATE...

I got the RPM GAUGE working. It turned out the male connector on the alternator was broken and not making the connection. I rigged up something temporarily to fix it and the RPM's work. I addition to the male connector broken, the swivel nut on the 2nd connection broke off so i had to rig something there too.

The fuel gauge worked too until I got to the gas station and turned her off. So i will be looking into that now. I am not sure which alternator connections affect what but a better more permanent fix should take care of both....

I'll post my updates

THANKS everyone