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Heater gauge

Tiny
PIPERJERKY
  • MEMBER
  • 1999 NISSAN PATHFINDER
  • 2.3L
  • 6 CYL
  • 4WD
  • MANUAL
  • 298,000 MILES
I had my water pump changed out last fall, then in the spring all of sudden the heater gauge started to go right up to high when I have only had truck running a short time. I have now changed the thermostat, the coolant sensor. I drove for a few days and the gauge keeps going up to max and then eventually will come back to normal. I finally took it in for coolant flush thinking I must have a blockage but shortly after driving away from garage the gauge went to high again. It seems when I shut off truck then restart the gauge goes right up to hot but will eventually come back to normal. Does anyone else have suggestions on what is going on?
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Sunday, April 7th, 2019 AT 10:21 AM

9 Replies

Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey PIPERJERKY,

From the information I have there is only a 3.3L engine in the Pathfinder for that year.

Do you have a 2.3L or 3.3L?

Just need to be sure for when giving to wiring diagrams etc.

I would advise we need to check the actual cylinder head temp vs the reading from the coolant temperature sensor to see if the reading is plausible.

It would also be worth checking the condition/tension of the drive belt to ensure that isn't too loose and causing the belt to split on the water pump pulley.

Regards, Joe
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Sunday, April 7th, 2019 AT 10:50 AM
Tiny
PIPERJERKY
  • MEMBER
  • 5 POSTS
Yes Joe, sorry its a 3.3L motor in there.
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Sunday, April 7th, 2019 AT 12:55 PM
Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey piperjerky,

So it looks like there are separate temperature sensors for the engine management and the instrument cluster.

On the sensor you replaced were there two wires or one?

The one for the gauge has just a yellow/red wire to it. It grounds through the engine.

Where as the coolant temperature sensor for the ECM has two wires. One black and one light green/red. It has its own ground.

Let me know which one you replaced and try and locate the single wire sensor if you changed the other one.

Should be at the top of the engine on the front.

Regards, Joe
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Sunday, April 7th, 2019 AT 4:06 PM
Tiny
PIPERJERKY
  • MEMBER
  • 5 POSTS
This is the sensor I have replaced:
Image (Click to make bigger)
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Sunday, April 7th, 2019 AT 6:44 PM
Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey piperjerky,

That does look like a single wire going to that sensor.

To be sure, can you pull back that outer wiring casing and tell me how many wires and what color they are please.

Regards, Joe
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Sunday, April 7th, 2019 AT 9:35 PM
Tiny
PIPERJERKY
  • MEMBER
  • 5 POSTS
Yes it is only one wire going to that sensor.
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Monday, April 8th, 2019 AT 5:13 AM
Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey piperjerky,

Can you get access to a scanner with live data?

Then we can monitor the temperature reading for the gauge vs the reading for the PCM sensor.

Can you locate the two wire sensor I was talking about?

Also have you checked belt tension?

Was the water pump that you changed obviously faulty?

If you start the car and leave it idling will it overheat?
Does the cooling fan cut in?

Regards, Joe
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Monday, April 8th, 2019 AT 8:45 PM
Tiny
PIPERJERKY
  • MEMBER
  • 5 POSTS
Hi Joe,

I looked under the hood again and can see many sensors but not really sure which on it might be. The water pump had gone so needed to be replaced. The truck has run good for six month then this started. I changed thermostat, coolant flush and that sensor on the top but not sure where the other on would be. I have tried to find out info on the net but have had no luck. It seems to always show the sensor that I changed already. When looking on Rock Auto it shows two different sensors. I am really not sure what to do now.
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Tuesday, April 9th, 2019 AT 10:36 AM
Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey piperjerky,

It looks like so far you have replaced essentially everything in the system and it should now be working correctly.

Do you own a multi-meter or a 12 volt test light?

I can run you through checking the wiring to the sensor.

At this point I would say you need to:

- Check the wiring to the sensor.
- Check the tension and condition of the belt drive.
- I would also advise then that if you changed the water pump and thermostat with aftermarket parts that you will need to remove these and test them.
- From cold remove the radiator cap and raise the engine revs, do you see any bubbles in the cooling system. If so I would take it to a shop that has a coolant engine block tester kit. This will check for exhaust gas in the coolant. A relatively quick test to rule out a head gasket issue.

Again does the radiator cooling fan cut in when it is overheating?

Regards, Joe
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Wednesday, April 10th, 2019 AT 7:23 AM

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