2nd Gen Non-Engine/Transmission Tach and Speedo not working.

[edgeman]

I have a 95 mannuel. The other day i was driving home and out of nowhere my speedomter and tach just stoped working. Now i have no idea where to even begin. Also my trip odometer and my odometer do not work also. If anyone has any info that would be great. Thanks.

 

[Signal73]

I believe the sending unit is mounted in the tailshaft of the transfercase for your model year as far as the speedo goes. As for as the tach and speedo going out at the same time, maybe check all your fuses to make sure the dash one didnt pop.

 

[edgeman]

i guess my other ? is, if the dash fuse went out would all the other gauges stop working. thanks for start tho.

 

[Dave M]

It could be your ESS (Engine Speed senser)... sometimes referred to as a CPS (Crank position Senser). It is mounted above the crank damper on my 97 and I believe also on your 95. It is a magnetic type senser that is mounted . 050 inch above the damper... use a business card or matchbook cover to set it.



Mine was bad on my 97 and the symptoms were no tach, speedo, alt not charging, no bulb check lights (like MIL etc) when turning key on but other dah lights worked and truck ran but battery was not charging.



The compuer (PCM) uses the pulses from the ESS to determine the engine is running and starts turning on the alt charging pules to alt from PCM. It cost me about $70 from NAPA and was easy to install. There is about a 2. 5 foot pigtail on it and the 3 pin connector is in front of engine on top toward drivers side kinda behind the oil fill cap. Try unpluging it and re-connecting or reset the gap.



Not sure if your 95 is the same but that fixed my 97.



Dave

 

[edgeman]

my battery seems to be charging just fine so im not sure if that is it but will unplug it and plug it back in and see what happens. thanks

 

[Dave M]

my battery seems to be charging just fine so im not sure if that is it but will unplug it and plug it back in and see what happens. thanks

I'm not familiar with what functions are controlled by the ESS on your 95 but that's what fixed my 97. Hopefully, someone familiar with your truck will verify what a bad ESS will do to your vehicle. Perhaps the tach and speedo are controlled by the same speed senser on your 95 and not the ESS... . we'll see.



Good luck,

Dave

 

[WestTN]

If you lose the speed sensor you lose exactly the functions you indicated.

 

[Dave M]

If you lose the speed sensor you lose exactly the functions you indicated.

Here's your answer... its the speed senser circuit.

 

[edgeman]

well i was wrong my batteries are slowing loosing charge so my guess is that it is my ESS. im going to NAPA to get a new one. thanks for the help everyone.

 

[MLee]

I would clean the bottom of the ESS, gap it, and use dialectic grease in the plug before spending the money.

Just a little bit of time expended.

 

[edgeman]

i cleaned it and nothin happend so it looks like i am getting a new one. thanks for all the help it is very helpfull

 

[Dave M]

I would clean the bottom of the ESS, gap it, and use dialectic grease in the plug before spending the money.

Just a little bit of time expended.

I would think if yor Alt is not charging you would get a Gen light on the dash along with other things like I mentioned I had with a bad ESS.



You could put your voltmeter at the 3 pin ESS connetor to look for 5 volts from PCM. Some PCM's supply 8 volts. The 3 pin connector has a voltage (like 5vdc for mine) on one pin supplied from the PCM, gnd on another pin and output pulses from ESS (you can't measure these) on the other pin. I only had 5 volts from PCM with the ESS disconnected. With ESS connected (the 3 pin connector plugged in) I had 0 volts. My ESS was shorting out the PCM.



You could have a bad PCM but it is not likely. The PCM is expensive. I paid $500 for mine from a dealer and it was not bad... turned out to be my ESS.



On my 97 the PCM supplies the regulator function to tell the alt to charge. If ESS is bad that won't happen and you won't get the 14 volts to charge battery. Verify that your alt is not charging (14 vdc) at battery before you assume your ESS is bad. As was stated earlier the speed senser is suspect if no tach or speedo. I'm not sure if your ESS also is needed for these functions to work but is is for my 97.



Here is my thread on ESS:



https://www.turbodieselregister.com...ons/184945-electrical-woes-maybe-bad-pcm.html



Good luck



Dave