93-97 Coolant Temperature Gauge Modification (2 Viewers)

[alia176]

I know this might be a bit off topic, but anyone have any resistors layin around? I'd much rather give you guys 5$ for 2 little resistors, then some company who wants like 8$ to ship a gram worth of parts...

Bryan,

I have two sets of extra resistors so let me know. If you're home from school any time soon, bring $5 to the house!

Later,

Ali

 

[RavenTai]

did some testing on the 93 gauge and to let you guys know the mod is in fact the same for the 93-94 gauges.

there was a few degrees diffrence here and there but close enough IMO, you can read the details starting arround post # 313

https://forum.ih8mud.com/showthread.php?t=53142

 

[alia176]

Another satisfied 80 owner with this mod. Thanks Raven!!

Ali

 

[Rookie2]

You can add Mr. Bryan to the list too. He did both the temp guage and the auto window up mod last week in like 8 minutes.


Rookie2

 

[tiorio]

It looks like your ambient temperatures are the same or slightly higher than mine. The more I think about it the more I'd love to see what temperatures your ECU is reading.

Finally got around to do at least a quick test today. Hooked up the OBD-II (AutoEnginuity ScanTool) and made a 15 min or so run. Here's what I found:

Needle parallel to white line on bottom of gauge, ECU says ~150F
Needle approx. 1/3 between white line and red line on gauge, ECU says ~174-178F

My temp maxed at 181, ambient temps mid 50s, stop-and-go driving. I'm fairly close the the range indicated. There are individual sensors for the ECU and the gauge, no? I forget...

 

[Beowulf]

There are individual sensors for the ECU and the gauge, no? I forget...

There are 3 stock temp sensors; A/C shutoff, ECU, and dash gauge. Some of us have added a fourth.

-B-

 

[RavenTai]

You can add Mr. Bryan to the list too. He did both the temp guage and the auto window up mod last week in like 8 minutes.


Rookie2

Cool is that 10 total now?

Finally got around to do at least a quick test today. Hooked up the OBD-II (AutoEnginuity ScanTool) and made a 15 min or so run. Here's what I found:

Needle parallel to white line on bottom of gauge, ECU says ~150F
Needle approx. 1/3 between white line and red line on gauge, ECU says ~174-178F

My temp maxed at 181, ambient temps mid 50s, stop-and-go driving. I'm fairly close the the range indicated. There are individual sensors for the ECU and the gauge, no? I forget...

So your gauge has been reading low since the mod correct? If you are maxing out at 181f that would fit, the gauge is suppose to center around 189 and this seams to be a pretty good center for most of us, yours seams to be running a bit cooler.

Thermosat Specs per the FSM

Valve opening temperature: 80 – 84°C (176 – 183°F)
Valve lift: 10 mm (0.39 in.) or more at 95°C (203°F)

Depends on how you look at it, it is suppose to crack open at about 179.6 I do not think that if yours was opening at 179 it would only be at 181 by the time it got to the end of the head (where the sensors are) I think your thermostat may be opening early probably not a big deal and maybe not worth futzing over, close enough and on the good side.

Have you replaced your thermostat yet? Was it OEM?

Like B said there are separate senders for the ECU and gauge, they both seam to agree that you are running cooler than most.

 

[tiorio]

So your gauge has been reading low since the mod correct? If you are maxing out at 181f that would fit, the gauge is suppose to center around 189 and this seams to be a pretty good center for most of us, yours seams to be running a bit cooler.

The truck has been running this way since the mod, the gauge vs. ECU readings have also been consistent.

Thermosat Specs per the FSM

Valve opening temperature: 80 – 84°C (176 – 183°F)
Valve lift: 10 mm (0.39 in.) or more at 95°C (203°F)

Depends on how you look at it, it is suppose to crack open at about 179.6 I do not think that if yours was opening at 179 it would only be at 181 by the time it got to the end of the head (where the sensors are) I think your thermostat may be opening early probably not a big deal and maybe not worth futzing over, close enough and on the good side.

Have you replaced your thermostat yet? Was it OEM?

I completely flushed my cooling system (back and forward, maybe sideways too) and replaced thermostat, fan clutch, couple of hoses, and filled with distilled/toyota red some 2000 miles ago, and had a quick partial drain/refill when I r&r'd the PHH a couple weeks ago.

I would not be surprised that I am running at the cool temp I am, but it does seem that my gauge position is lower by ~10F at the same actual temp as other modders. So I think the gauge is accurate, but my range is 140 (pegged cold) to prolly 234 (pegged hot) by extrapolation. Accurate enough for me, but an interesting variation nonetheless!

Either way, I'm VERY HAPPY with this mod, thanks to all who contributed!

 

[Sully]

Did the mod yesterday with a little help from a friend who used to do aviation electrics for the navy. It was really pretty simple. I look forward to getting my truck put back together to see the results. Thanks RT.

 

[jcolegrove]

did mod a month ago. runs consistently at parallel to the horizon almost all the time. no data on OBD temp or such- sorry.

 

[RavenTai]

Mods # 11 & 12

good deal.

mine has beeen doing the same as before, near level most times, pops up a bit with extended idle time, especially with the AC on.

 

[semlin]

anyone got an extra set of resisters they want to sell? my truck is finally running so I want to do the mod gauge before the end of the month when i have a long road trip.

 

[RavenTai]

there was a pair of resistors in the box,

have you not recieved your package?

 

[RavenTai]

there was a pair of resistors in the box,

have you not recieved your package?

 

[semlin]

no sir. when did you send it??

 

[semlin]

ok add me to the list. many thanks RT, I got it and was already to mod it when the penny finally dropped and i realized it was already modded

turns out I am running 2 or 3 needle widths above the middle line so I am very glad I got it now to figure out why.

incidentily, I noticed that when I turned it off then turned it back on to ign without restarting, the needle did not return to the spot it was before, nor when I restarted it right after. It seemed to drop a needle width or so. is there any memory factor on these gauges?

 

[Darwood]

ok add me to the list. many thanks RT, I got it and was already to mod it when the penny finally dropped and i realized it was already modded

turns out I am running 2 or 3 needle widths above the middle line so I am very glad I got it now to figure out why.

incidentily, I noticed that when I turned it off then turned it back on to ign without restarting, the needle did not return to the spot it was before, nor when I restarted it right after. It seemed to drop a needle width or so. is there any memory factor on these gauges?

I think the reason the gauge doesn't go back to the same spot is due to the input voltage. Without starting the motor your voltage will be about 12.7 volts instead of 14.4 volts when running. Going by Raven's experiments and some of my calculations, the input voltage will effect how the gauge reads.

Semlin, try to get an OBDII scanner on there if you can to read what temperature the ECU thinks it is. Also how old is your radiator and is there any crud in it? I don't recall if you replaced it when you did your head gasket.

 

[Beowulf]

Semlin, try to get an OBDII scanner on there if you can to read what temperature the ECU thinks it is.

That will be a neat trick on his '93.

-B-

 

[Darwood]

That will be a neat trick on his '93.

-B-

Hehe you are right. I'm retarded.

I just naturally assume everyone has the magnificent OBDII on their trucks like me.

 

[RavenTai]

Semlin you are the lucky #13

The gauge is slightly voltage sensitive at the extremes, it is not affected around the middle, engine on you should have 14.x volts and this is where it is considered most accurate, be aware the coolant temps raises quickly for a few minutes when you shut down, the head is still hot but no coolant circulates so the coolant in the head (where the sensor is) goes up, as soon as you start again the temperature will decrease rapidly.

There are several that report slightly elevated temperatures, so far no major overheats recorded by the gauge that I have heard of, the temps are not excessively high witch brings up the question does your truck need work or not? I am in the same spot, why is it some get a dead steady needle? what is wrong with our trucks that they are not? I have done all fo the PM except for a new radiator.

One of the neat things about the gauge mod will be when the first one of us starts tinkering and finding out what actually helps as you will have direct feedback on what works and what does not.

So who is going to be the first one to plunk down several hundred for a new 93/94 rad?

one thing I am considering right now is a 65/35 water/coolant mix to see if that helps any, I will loose some freeze protection but I do not need much, it rarely gets below the teens here, below 0 F is a once in a lifetime thing