Archived Need Help Electrical I think>>>

[Hddriver]

95 2500 4x4 111000 miles

Synptoms:

Electric guage reads 12 volts normally 14 so it is showing low volts I think

Tach Dead

The three idiot lights to include the "WAIT TO START" and "water in Fuel" are inoperative

transmission Will not shift into over drive

"Overdrive off" button on dash normally dark, lights up when you push it to indicate that the overdrive in inactivated. The light is out and pressing the button does nothing.

Everything else seems to be normal



What is causing this???

Any ideas?



Help Please...

CHuck

 

[Joe G.]

Chuck,



Have you checked all your fuses?



What happens if you turn on your head lights? Are they as bright as normal? IF not try charging your batteries and see if the symptoms go away. If so your batteries may be junk.

 

[Alan Reagan]

I can't remember what they call it on the 98 and earlier models but I believe it's the ECU(??). That controls guages and with the PCM controls voltage regulation. Start by removing those connectors, spraying contact cleaner in there and if possible, burnishing the contacts a little to clean them up. Reinstall.



Also, check for problems where you have ground wires. Improper ground will cause the symptoms you are having.

 

[Bigramguy]

Check the tach sensor on the front of the engine. The PCM needs a RPM input to function. If it doesn't see this,then it doesn't know the truck is running. It will also cause the tach not to register properly,or at all.

 

[JohnMcIntyre]

Pay it forward.....eventually!!

I was caught out recently on an unrelated problem, but I'm convinced that you'll get a resolution here a whole lot faster than elsewhere. FWIW, I also believe that your problem is electricity related, or more precisely a lack of it. After you've checked the fuses, go look for the circuit breakers especially any aftermarket ones, usually to be found in aftermarket HiFi installs and camper/tow packages occasionally... .

I hope you get to the bottom of this asap. Good luck!!

 

[bubba_zanetti]

I agree on checking the tach sensor... but I suggest checking the connector behind the upper radiator hose.



Mine was corroded and caused the same type of symtoms... some WD-40 fixed it.

 

[Josparkz]

There is a 125 (or so )amp fuse in the box under the hood . That goes from your alternator and feeds most if not all of the circuits in that power/relay box , underhood , driver's side . If you hit that open stud on the alternator with your oil filter wrench it does it's job. It made me think I killed the alternator , till I opened a book and find out about it. It was a dealer only item , but I got a smaller fuse , maybe a 75 ampere one , reamed the holes and bent the prongs and got everything running till I got the correct fit use .

 

[Lift Tech]

I had the exact same symptoms last month on my 97, got to buy a new PCM 497. 00$. First check the 12v and negative inputs to the pcm at the pin connectors if these values are correct check the 5v output value at the crank sensor connector if not at least 4. 7 volts you have lost the 5v circuit insde the pcm. On the bright side the new pcm I installed had been updated twice now the trans operates better and the charging system is more constistant.