Couple minor electrical issues w/ 1165

[hdfireman]

Just bought a 1165 and has 2 issues. The Tachometer works most of the time. It will drop to zero for a second and come back, seems to do it more at idle. I checked the plug on tach and it is secure. Bad sending unit? The other issue is the fuel gauge doesn't work. When you power up the truck it pegs out past full. The truck has a new updated sending unit in it by previous owner and it still doesn't work. Anything to try before getting a new gauge? Anyone have a link to a service manual or some things for me to check. Thanks in advance fellas and stoked to have this HMMWV.

 

[Retiredwarhorses]

The tachometer gets its signal from the generator, so take your pick, bad Tach, bad connection, slipping serp belt…I’ve seen this happen and it’s a momentary issue, so I could care less, because I’ve seen it happen in so many trucks, I’m inclined to believe it’s normal.

 

[hdfireman]

The tachometer gets its signal from the generator, so take your pick, bad Tach, bad connection, slipping serp belt…I’ve seen this happen and it’s a momentary issue, so I could care less, because I’ve seen it happen in so many trucks, I’m inclined to believe it’s normal.

Thank you sir.

 

[hdfireman]

Anyone on fuel gauge or have manual so I can track it down?

 

[Mogman]

Anyone on fuel gauge or have manual so I can track it down?

There are many TMs available for download here on SS that have the information you need.

Basically all old school automotive temp, pressure and fuel gauges operate the same, with the lead open to the sending unit it will read max in one direction and with that lead shorted to ground it will read max in the other direction, the direction itself can be ether way depending on how the gauge is engineered.

So take the lead off of the sending unit, note which way it is maxed out then momentarily short it to ground and it should max out in the other direction, if it does not do this then there is a problem with the gauge itself or the wiring to the sending unit, if it acts like it should it still could be a gauge issue but that is someplace to start.

 

[hdfireman]

I didn’t have time to drop the tank enough to access the sender so I did it at the gauge. 28A as stated above was unplugged and it remain pegged past full I grounded that pin at the gauge and the gauge did not move, stayed pegged past full. So I’m thinking it’s gauge. That seem correct??

 

[Mogman]

That is correct, 27 is 24V power 58 is ground and 28 is the sending unit.
Double check the power and ground to the gauge.
The sending unit is a "GM 90" so it should ohm out between 0-90 ohms to ground, IIRC 90 ohms is full