Finally got me a deuce!

[cattlerepairman]

So.. putnthe new temperature sending unit in, and my rpm guage started acting up.

It was off.. then by the time u made my way around to the passenger side to check the transmission fluid it was working.

I drove it about 40miles, rpm guage would come and go..

Temperature guage still not functioning, now the hour meter and rpm guage went out.

But I did manage to make it to a shop.

I'm guessing maybe a grounding issue, with the instrument cluster?

Sounds right. The ground is provided by the lock screws that hold the gauge cluster to the dash. They often corrode a bit.

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[Mullaney]

So.. putnthe new temperature sending unit in, and my rpm guage started acting up.

It was off.. then by the time u made my way around to the passenger side to check the transmission fluid it was working.

I drove it about 40miles, rpm guage would come and go..

Temperature guage still not functioning, now the hour meter and rpm guage went out.

But I did manage to make it to a shop.

I'm guessing maybe a grounding issue, with the instrument cluster?

.
My best guess would be a grounding issue on all but the Tach. I would suggest a good clean place on the dash plate and another on the dash panel with a ground wire between them. Use a pencil and shorten the ground - but leave 2 or 3 feet of ground so you can work on the dash plate in your lap if you want to. Using the pencil will create a nice coil that keeps all the excess in a neat organized way.

It might even be worth finding a ground strap for the cab of the truck. It should have one, but who knows what may have happened to yours. Clean a spot on the cab and clean a spot on the frame... Bolt the ground in place and then you will have a known good grounding point for your gauges.

 

[Balalala]

The tach sensor might have to be adjusted - mine does the same thing and I haven't messed with anything on the gauge cluster. The tach sensor is a magnetic unit near the flywheel. I think the best way to get to it is to pull the dog house. There's a sensor adjustment procedure in volume 1 of the maintenance TM you can try:

View attachment 897205

Thanks, hopefully the shop will figure it out for me. I haven't much faith, but he did say they had worked on a deuce or two.

Not sure guages are required to pass an inspection, but I guess I will find out tomorrow.

 

[Balalala]

Sounds right. The ground is provided by the lock screws that hold the gauge cluster to the dash. They often corrode a bit.

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They both went out within 3 or 4 startups of the truck, I'm hoping it's a ground issue

 

[Mullaney]

Thanks, hopefully the shop will figure it out for me. I haven't much faith, but he did say they had worked on a deuce or two.

Not sure guages are required to pass an inspection, but I guess I will find out tomorrow.

.
Hopefully you will pass the inspection!

Yeah, those 4 quarter turn fasteners (Dzus) on the gauge plate are supposed to create the ground but after 30 or 40 years things get a little corroded.

 

[vmax]

Hello guys!

I have been creeping around here for a year or so, learning much..

I must thank you all for giving me the advice needed to find the right truck! Even if I never spoke to you personally.

Here she is, m35a3! I have much to learn and do.. looking forward to it!

16hour drive home... couple break downs along the way.. let the adventures begin!

Congratulations!

 

[Balalala]

It passed the inspection with no issues!

Looks like the rpm guage sorted itself out.. now to figure out the temperature guage.

I did make it home with it, the old girl ran flawlessly.

After getting home i opened up the hood, noticed some coolant had leaked. Upoj further inspection it looks like my lower rad hose is cracked, anyone have a part number for me? *found a replacement*

I am fully licensed and legal!

 

[ToddJK]

It passed the inspection with no issues!

Looks like the rpm guage sorted itself out.. now to figure out the temperature guage.

I did make it home with it, the old girl ran flawlessly.

After getting home i opened up the hood, noticed some coolant had leaked. Upoj further inspection it looks like my lower rad hose is cracked, anyone have a part number for me? *found a replacement*

I am fully licensed and legal!

That's good news! Make sure to check your wires on the temp gauge. When mine quit, I bought a new gauge and sending unit and it still didn't work. The wire ended up being broken internally and there was no way of seeing it. I just happened to find out when I ran a wire bypassing the one that goes from the gauge to the sending unit and it worked. Same thing happened to my horn a while back before my solenoid pooped out.

 

[Balalala]

That's good news! Make sure to check your wires on the temp gauge. When mine quit, I bought a new gauge and sending unit and it still didn't work. The wire ended up being broken internally and there was no way of seeing it. I just happened to find out when I ran a wire bypassing the one that goes from the gauge to the sending unit and it worked. Same thing happened to my horn a while back before my solenoid pooped out.

Thanks. Perhaps that will be my next move, splice into the wire at the sending unit and run it to the guage

I removed the panel, checked the grounds. Unplugged it, and plugged it back in..

I kept the old sending unit, perhaps I can put it in some hot water and use it to test with until I get my rad hose replaced

 

[ToddJK]

Thanks. Perhaps that will be my next move, splice into the wire at the sending unit and run it to the guage

I removed the panel, checked the grounds. Unplugged it, and plugged it back in..

I kept the old sending unit, perhaps I can put it in some hot water and use it to test with until I get my rad hose replaced

Hopefully you get it figured out, keep us posted.

 

[Balalala]

I see there are 2 plugs going into the temperature guage.. is one a ground? Or does a current flow through one when the ignition is turned on?

 

[ToddJK]

I see there are 2 plugs going into the temperature guage.. is one a ground? Or does a current flow through one when the ignition is turned on?

One goes to the sending unit while the other is the power from the accessory switch.

 

[Balalala]

One goes to the sending unit while the other is the power from the accessory switch.

Gotcha, I seen the shorter wire going to I guess the accessory switch. So that should have power coming from it, and the other plug goes all the way to the temp sending unit.

 

[ToddJK]

Gotcha, I seen the shorter wire going to I guess the accessory switch. So that should have power coming from it, and the other plug goes all the way to the temp sending unit.

Correct.

 

[HDN]

@Balalala do you have any of the TMs for the truck? I recommend downloading all the PDFs, which I believe are all searchable with CTRL+F. You can find them here if you don't already have them.

 

[Balalala]

Yes I downloaded most of the TM's thanks for the link though!

Does your guys' temperature guage move a tiny bit, when you turn the ignition on?

 

[cattlerepairman]

Yes I downloaded most of the TM's thanks for the link though!

Does your guys' temperature guage move a tiny bit, when you turn the ignition on?

Yes, the gauges move when powered up

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[ToddJK]

Yes I downloaded most of the TM's thanks for the link though!

Does your guys' temperature guage move a tiny bit, when you turn the ignition on?

Yup

 

[Balalala]

Ok so I pulled out the multi meter.. temp guage is getting 24volts from the accessory switch. The ground has good continuity, and the temperature sending unit is currently sending out 6.8ohms.

I didnt put temp sending unit in hot water, to verify the ohms changed, but I think I have to assume that the guage has failed. You guys agree?

 

[Balalala]

@Balalala do you have any of the TMs for the truck? I recommend downloading all the PDFs, which I believe are all searchable with CTRL+F. You can find them here if you don't already have them.

I followed the troubleshooting instructions in the TM.

The sending unit when in hot water is down to 2.5ohms. Ambient temp it's sitting at 6 or 7 ohms. I measured it at where the wire plugs into the gage, as well as directly from the sensor and the ohm reading was the same. So it appears functional, and the wire is intact.

When I ground out the sending unit pin on the gage, it does peg the meter all the way to the right. I have also verified 24volts going to the guage.

I found where the gage is grounded to the front panel, it appears to be in good condition.