Engine/Transmission (1994 - 1998) no tach, speedo

[zstroken]

Changed convertor out, when I started the truck back up, no tach, speedo doesn't work, I have the trans relay jumpered out. The transmission starts in third. I had the transfercase, and transmission out. I haven't looked over the wiring yet(I ran out of time). What puzzles me is the tach not working. I have oil pressure, and the voltmeter is reading. I don't think the alternator is charging though. I don't have AC, so I can't tell if that is working or not. Any body have any ideas?? I imagine I have cut a wire somewhere would a shorted wire around the transmission area cause the tach to quit working?

Thanks

Dan

 

[zstroken]

Looks like the 5 V that feeds the transmission temp sensor and Governor pressure sensor is the same 5V that feeds the crankshaft sensor. I am guessing it is the same signal that feeds the speedometer also.

 

[tp0d]

If the crank sensor doesnt work, the PCM will not enable, and all the things you described above will happen. Possible you pinched a wire, but that would blow a fuse. If nothing is blown, check the crankshaft sensor plug for voltage with key on. If ya have +5v to ground, its dead. I hear they can go tits up for no reason.



good luck



-j

 

[zstroken]

Shouldn't the speedo still work as long as the key is on and the engine is off??

assuming 5V is present. Is the oil pressure gage PCM controlled??

 

[SKnapp]

I had this problem on my 92 dually a few years back, keep blowing fuses, burnt some wiring what a night mare couldn't figure it out for the life of me, finally broke down and took it to a good friend who is a dodge mech. he found that some wires had rubbed through just behind engine. so my guess would be yes you probably pinch them.

 

[zstroken]

SHould probably post an update. I checked the 5V that supplies the transmission sensors, cran sensor, VSS, and with key off meter read 0. 001 when I turned the key on in jumped to 0. 008 . Disconnected sensors still 0. 008 it might have jupmed to 0. 009. Looked over wiring could not find any shorts. I then hooked up an ECM I have out of a 1997 5 speed truck. Had the 5V started the truck with sensors hooked up and all of the gages work. Good indication of bad ECM is watch for the wait to start indicator, as well as water in fuel. I believe the generator light will come on also. WIth the bad ECM none of that happened. So if anybody has an ECM for a 1997 auto give me shout.