Engine temperature gauge has no power to sending unit.

CDLong wrote

Thanks Jim, I'll check the resistance in the wire.

Right.
So you can ground the R/W wire to the block and check from the instrument plug to any ground in the cab, and the wire should be close to 0 ohms.
You can plug it into the sender and it should read close to 73 ohms with a cold engine.
You can check the sender itself from where the wire attaches and again see ~73 ohms (cold)

If you get infinity (OL) with the first one there is a break in the wire.
If you get (OL) with the second and third one the sender is bad or someone used Teflon tape and the sender is not making a good connection to the intake manifold.

I don't include option three (cab isolated from ground) because apparently the oil pressure gauge seems to work.

ArdWrknTrk wrote

CDLong wrote

Thanks Jim, I'll check the resistance in the wire.

Right.
So you can ground the R/W wire to the block and check from the instrument plug to any ground in the cab, and the wire should be close to 0 ohms.
You can plug it into the sender and it should read close to 73 ohms with a cold engine.
You can check the sender itself from where the wire attaches and again see ~73 ohms (cold)

If you get infinity (OL) with the first one there is a break in the wire.
If you get (OL) with the second and third one the sender is bad or someone used Teflon tape and the sender is not making a good connection to the intake manifold.

I don't include option three (cab isolated from ground) because apparently the oil pressure gauge seems to work.

Weather here hasn't been cooperative. I finally checked the wire with it connected to the sender. Engine was cold, hasn't been operated since yesterday morning. You can plug it into the sender and it should read close to 73 ohms with a cold engine. I have 62 ohms
You can check the sender itself from where the wire attaches and again see ~73 ohms (cold)I have 65 ohms. I couldn't check the wire disconnected from the sender. No helper was available, and I couldn't get a good ground. I did get all the dash light bulbs tested. They're all good.

CDLong wrote

ArdWrknTrk wrote

You can plug it into the sender and it should read close to 73 ohms with a cold engine.
You can check the sender itself from where the wire attaches and again see ~73 ohms (cold)

I have 62 ohms
You can check the sender itself from where the wire attaches and again see ~73 ohms (cold)I have 65 ohms

65 ohms isn't bad.
With that the needle should budge but not sweep up into [NORMAL]
The other way you could check the gauge is to backprobe the sender wire at the plug behind the cluster to ground (any metal frame of the dash) and with the key on the water temp should be pegged.

While the sender seems a little out of range I think you should confirm it's bad, and the gauge good, before condemning it.
If both ohm readings are the same (and the meter battery is good) then the wire shows 0 added resistance.  

Unfortunitely, dash is out of truck, waiting on new cable that shows what gear the auto trans is in. The meter seems to be correct. I checked 2 Ryobi batteries, 20V each. Truck battery is 12.4 V with engine not operating. sender is new. I installed it when I did the major tune up. I remember the gauge did not move with the old sending unit or the new sending unit.

CDLong wrote

Unfortunitely, dash is out of truck, waiting on new cable that shows what gear the auto trans is in. The meter seems to be correct. I checked 2 Ryobi batteries, 20V each. Truck battery is 12.4 V with engine not operating. sender is new. I installed it when I did the major tune up. I remember the gauge did not move with the old sending unit or the new sending unit.

Because the cluster is out is why I say now is the time to test from where the plug goes in all the way thru the cluster, IVR the gauge back out to the plug.
Then again because you know the fuel and oil gauges work if you put power to the IVR and check at the temp gauge in and then out all the way back to the plug you will know for sure that part of the cluster is good before you go putting back in.

Being it sounds like the new sender and wire back to the plug is good is even more reason to check the cluster.
Dave ----

FuzzFace2 wrote

CDLong wrote

Unfortunitely, dash is out of truck, waiting on new cable that shows what gear the auto trans is in. The meter seems to be correct. I checked 2 Ryobi batteries, 20V each. Truck battery is 12.4 V with engine not operating. sender is new. I installed it when I did the major tune up. I remember the gauge did not move with the old sending unit or the new sending unit.

Because the cluster is out is why I say now is the time to test from where the plug goes in all the way thru the cluster, IVR the gauge back out to the plug.
Then again because you know the fuel and oil gauges work if you put power to the IVR and check at the temp gauge in and then out all the way back to the plug you will know for sure that part of the cluster is good before you go putting back in.

Being it sounds like the new sender and wire back to the plug is good is even more reason to check the cluster.
Dave ----

I assume I can use small alligator clips to connect to the plug, but how would I connect the wire to the ribbon?

Yes, an alligator clip can easily connect to the sender.  And if you are careful you should be able to use one on the ribbon.  If I remember correctly the ribbon wraps around the connector and sticks out a bit, so you should be able to gently put a clip there.  Gently.  Or just use the probe from the meter to touch the trace.

I was thinkin' a male spade butt connector on the ribbon end of the jumper wire so it could lay on the ribbon. Harbor Freight has small plastic clamps but I don't know if there's enough room in the panel to use them.

CDLong wrote

I remember the gauge did not move with the old sending unit or the new sending unit.

Which leaves you with either the instrument itself or a bad flex.
It's pretty easy to see tears and corrosion on the mylar.

Our member Blue Truck Parts (where you probably got the indicator cable) has a refinished temp gauge on eBay for $40, though it might stick out on an old cluster.
There are other used 'known good' ones there for ~$30 delivered.

I have been considering a refurbished gauge. Thanks Jim.

If you test for continuity from the ICVR output to the tab for the water temp sender wire what do you get?

It's interesting that these gauges work by sending power through a spring that uncoils when hot, much like an electric choke functions.

If you tested the cluster on the bench you would know if it was the gauge or the ribbon it was not that hard when out.
Dave ----

I appreciate everyone's help. The gauge is bad.

Had to figure when you said there was no voltage to the sender and the resistance through the wire and sender was 65 ohms.

CDLong wrote

Unfortunitely, dash is out of truck, waiting on new cable that shows what gear the auto trans is in.

Hi CDLong,
Do you remember from whom you got the indicator cable?

Try Blue Truck Parts eBay store.
He's a member here on the forum and has good feedback.

Yesterday:

dirtymac wrote

I bought his gear shift cable and have been very happy with it.  I've already had to disconnect it 4-5 times and it goes back just right each time.  I did have some issues with the included 3-D printed clip but it worked well enough with my one original clip that I've made no complaints.

And his screen name is thisoldpart.

The guys are correct. Blue Truck Parts. I also got a refurb engine temp gauge from them. I may be gettin' parts for the window & door lock switches from them once I remove the door panel.

In fact, I was trying to find the member’s screen name.
For Jim, in the re-thinking 3G page thread.


So Gary, you found it:
 

Gary Lewis wrote

And his screen name is thisoldpart.

BigBrother-84 wrote

CDLong wrote

Unfortunitely, dash is out of truck, waiting on new cable that shows what gear the auto trans is in.

Hi CDLong,
Do you remember from whom you got the indicator cable?

The only issue I had installing the new cable was the clamp on the steering column. Every time I tried installing the collar, the clamp would come out. Finally got it to stay in.