Do all first gen trucks have the under dash plug in for the facotry installed tach?? i just removed the one out of our 93 to sell it and i saved the tach and the wire that comes out of it with the plug. i undid the plug from under the dash where it was plugged in. and dont know whether to go through the trouble to save the whole tach harness with sensor. thanks. Brandon

 

Only I/C trucks came with the wiring harness for the factory tachs.

 

if you want to put it on a 91 non i/c truck you need all of it, or at least tach and senser you could make you own harness, but for a intercooled truck i think all you need is the tach

 

SWEET, thanks for the replies you guys rock.

 

91.5's didn't have it. I don't think that early 92's did either.

 

For a nonIC'd truck you'd also need the pcm and crank sensor from the factory tach truck. We all know what problems are associated with the pcm and crank sensor. Why would a nonIC'd truck want any of that electronic pcm controlled garbage?

 

My Intercooled 91.5 isn't wired for it. I think the easiest way to tell is see if there is a voltage regulator on the firewall. If the voltage regulator is present you have a 90% chance of NOT having the under dash connector. The 91.5 transition year seems to be made from left over 90 & 91 parts until they were depleted.

 

My current 91.5 is the same, I haven't looked for a plug but seeing as there is no crank sensor, and there is a voltage regulator I don't think its likely. However, my first Cummins Dodge, a 91.5 also, had one. I have also seen a factory tach on a non intercooled 91, but it was in a picture and I didn't get a chance to see if it was a full on 92+ setup w/ no regulator and the crank sensor, if it just had the crank sensor, or something else entirely.

 

My 91.5 does have the tach plug, I was told that it gets it's signal from the pcm. I have never tried to plug a tach in it so I could not tell you if it works.

 

I can see the crank sensor on the crank pulley. it looks like two bolts hold it on. looks easy to get to. right in front of my eyes on the front of the block the crank sensor wire splits and has a connector near the thermostat where it unplugs. the wire comes from the same harness where the TPS wiring is. do all trucks have this part without the sensor section that runs down??

 

Mines a 91 non-intercooled had the factory tach on the dash installed at the dealer ship, before customer received it.
No pcm, crank sensor out front, wire thu the fire wall,..........I guess the pcm could be hidden under the dash as i have not fallowed the wires past the fire wall.
I have a voltage reg on the fire wall.
Flash

 

I have a truck that was built in January 92 and it has the wiring harness for the factory tach. I have a factory tach for it and it does work. Also is this considered an early 92?

 

They usally change years in the middle of the year so a January or 01/??/1992 would be a late model 91.


Flash

 

Iterresting because it was assembled on 1/24/92 and it is badged as a 92. good to know

 

Whoops !!!
They start the model year in Sept of the preceeding year....

The build date in Jan '92 would be a late '92...
Like when they switched from the 12V to the 24V in LATE '98...The switch was in Jan or Feb of '98- I forget...