Water temp gauge
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Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
Yes, lots of us have come across that problem. The first question is if your oil pressure and fuel gauge are working. If not, you have an Instrument Cluster Voltage Regulator problem. I have a page on my web site about that: ICVR - Gary's Garagemahal
If your oil and fuel gauges are working then it is likely to be the sending unit that is screwed into the engine. This page on my web site explains how the circuitry works and how to troubleshoot it: Fuel Tank Selector & Gauges - Gary's Garagemahal
If your oil and fuel gauges are working then it is likely to be the sending unit that is screwed into the engine. This page on my web site explains how the circuitry works and how to troubleshoot it: Fuel Tank Selector & Gauges - Gary's Garagemahal
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From: Angier, NC
Johno If you don't have one yet buy a factory service manual for your truck. It will have all this information in it and help you locate & test systems.
Then when you get stuck on something or even want to double check you under stand it ask here.
Dave ----
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From: Victoria, Australia.
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From: Denver Metro Area, CO
Remove the wire from the sender; with the ignition switch in RUN and engine not running, connect the wire to a good nearby ground and teh gauge should peg all the way on the hjigh side; un-ground it and it should return to the full low side.
Don't ground the wire for real long but short periods for diagnostic purposes are OK.
If the gauge swings fully as you ground/unground the wire, this generally implies the gauge and wiring are OK (the correct test is listed in Gary's EVTM that he linked to above and involves resistors being placed inline in that circuit but most people don't have those) and the problem is in the sender which you should then replace...
That sender needs to supply an electrical ground to the engine block so don't load it up with lots of sealer.
BTW have you gotten yourself any sort of factory (or even aftermarket) books or other documentation to help you with this thing?
Two more questions if I may - how old are you and what is your experience with American vehicles of this age (non-EFI)?
Don't ground the wire for real long but short periods for diagnostic purposes are OK.
If the gauge swings fully as you ground/unground the wire, this generally implies the gauge and wiring are OK (the correct test is listed in Gary's EVTM that he linked to above and involves resistors being placed inline in that circuit but most people don't have those) and the problem is in the sender which you should then replace...
That sender needs to supply an electrical ground to the engine block so don't load it up with lots of sealer.
BTW have you gotten yourself any sort of factory (or even aftermarket) books or other documentation to help you with this thing?
Two more questions if I may - how old are you and what is your experience with American vehicles of this age (non-EFI)?
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Joined: Jul 2010
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From: Northeast, OK
Yep, on several counts. 
Yes, the sender grounds through the block. Which is why Chris told you to ground the wire to the block to test, and not to load the sender up with sealer when/if you put a new one in.
Yes, the sender grounds through the block. Which is why Chris told you to ground the wire to the block to test, and not to load the sender up with sealer when/if you put a new one in.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
Ok, I don't want to talk down to you or demean you, but will spell it out very clearly:
- Pull the connector & wire off of the temp sender. It should slide right off if you pull it directly away from the sender since most of the connectors slide on/pull off. But, I have seen some that have a ring-tongue terminal on the end that goes over a stud on the sender and a nut goes on top to hold it on. In either case, remove the wire from the sender.
- Hold the connector against the engine block. This is called "grounding it" since the engine block is ground.
- Meanwhile, someone else needs to be in the truck with the key on, but the engine not running, watching the gauge. If it goes to full scale fairly quickly when you ground the wire then the problem is the sender.
- If the gauge doesn't move then the problem is not the sender and is in the wiring or the gauge itself. In that case report back and we'll take the next step.
