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peterpete190, Auto Technician
Category: Mitsubishi
Satisfied Customers: 28764
Experience:  Auto repair Technician with 17 years experience.Past ASE and other certifications.
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I have a 1997 Montero Sports LS. The temperature gauge goes

Customer Question

Customer: This is Selvin, I have a 1997 Montero Sports LS. The temperature gauge goes up when I stopped at lights. The fan works whenever I turn the heat or AC on but doesn't work automatically. I checked fuses and they are all ok. Any idea what the problem is?
JA: Thanks. Can you give me any more details about your issue?
Customer: The temperature gauge is normal when I am driving, the problem only occurs when I am at a stop light after leaving stop light the gauge returns to normal.
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $18) to post your type of question to Mitsubishi Experts (you only pay if satisfied). There are a couple customers ahead of you. Are you willing to wait a bit?
Customer: Yes.
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Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Jerry replied 1 year ago.

Hello and welcome. My name is ***** ***** you for visiting the site, I will be happy to assist you today.


Is that a 1997 V6 with an electric radiator fan?

Customer: replied 1 year ago.
Expert:  Jerry replied 1 year ago.

I don't seem to have anything on that, but wait there may be another expert who has more. I will opt out and open it back up. Please DON’T REPLY to this post as that will lock the question back to me, someone should be along shortly, I’m sure, thanks and sorry I wasn’t able to help with it.

Expert:  peterpete190 replied 1 year ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Do you still need help with this here?

Let me know so we can continue,thanks Pete.

Customer: replied 1 year ago.
Expert:  peterpete190 replied 1 year ago.

Is the temp gauge rising rapidly with this issue here?

Customer: replied 1 year ago.
No, It rises slowly when I am at stop signs.
Expert:  peterpete190 replied 1 year ago.

O.k.,there is a temp sensor for the engine computer and if this sensor is sending the incorrect info on how hot the engine is this will cause the fan to stay disengaged and cause an over heat issue at a stop.The sensor looks to be located on the upper radiator hose outlet housing.I have seen plenty of these sensors fail on other models before needing replaced.Below is a diagram of this sensor.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
I forgot to mention that I have just replaced both temperature sensor.
Expert:  peterpete190 replied 1 year ago.

O.k.,with it not over heating when driving it this doesnt sound like something like a coolant restriction or cylinder head gasket leak here sounds like the engine fan isnt being commanded on when it starts to heat up and if the fan works normally with the ac on then the relays and fan are o.k. and since the engine coolant temp sensors were already replaced this may be due to a fault with the engine computer itself.I have seen the internal circuit that commands the fan on for an over heat or heating up issue in the engine computer fail before in the past and had to replace the computer for this issue here.This sounds like what may be occuring here.

Make sure the air flow through the ac condensor and radiator isnt plugged with debris as this can also cause this issue.

Thanks Pete

Customer: replied 1 year ago.
If I understand you correctly, are you saying that the computer that controls all the vehicle operations will need to be replaced. Is that correct ?
Expert:  peterpete190 replied 1 year ago.

If the computer is not commanding the coolant fan on when the engine starts to heat up to where the fan should be on and the coolant sensors were already replaced and the fan does work with the ac on this sounds like the engine computer itself that controls all other operations may be at fault internally.It may just be the fan circuit in the computer that is at fault and all other functions may be o.k.

I dont have a diagram of this model here to tell you how to test this but I have seen some computers fail like this before in the past.

Thanks Pete

Customer: replied 1 year ago.
I will need to take it to a mechanic shop to confirm this.
Expert:  peterpete190 replied 1 year ago.

O.k.,if you need anything else let me know and feel free to rate my help if you like.

Thanks Pete