Join Date: Jan 2010
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tachometer not working '96 peterbilt
We just bought a '96 Peterbilt 378 with a 435hp 3406e and 1.34 million miles. The valve cover says 435hp but we were told that the ecm says 500hp and verifies that many miles, but it doesn't run like 500hp. It seems that our '03 C15's with 425hp can outrun it by just a little bit. We have noticed that the tachometer doesn't work at all and it looks like they just replaced it with a brand new one. I pulled the dash panel out (which i love how easy that is to do on a pete) and wiggled the plug and even unplugged it and plugged it back in all while it was running and the gauge didn't move at all. Any ideas what could be looked at next? The pyro also doesn't work. It looks like there are two wires for that going to the sensor in the exhaust. Same thing, i wiggled the wires and nothing.
Other than that, with that many miles, it seems to run ok. The highest I could get the boost while pulling a load was about 22-23 psi if the boost gauge is reading correct. I'm assuming they have done an inframe with it at some point because it doesn't smoke at all and the head has no paint at all on it and the oil pan is squeaky clean.
Any info as to what to look for and maybe any thing else that is problematic on this year and model of Pete would be greatly appreciated. Thanks everyone!