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Amedee, Chrysler Technician
Category: Chrysler
Satisfied Customers: 24093
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Grand voyager: plymouth..overheating..cooling relay

Resolved Question:

1999 plymouth grand voyager overheating. we have replaced cooling fan relay, and computer. cooling fans will come on sometimes and other times will not causing motor to overheat
Submitted: 6 years ago.
Category: Chrysler
Expert:  Amedee replied 6 years ago.



You might just have a bad engine coolant temp sensor. THis is very common. This sensor goes bad all the time causing this problem. In addition, if the coolant is low, it will not give the temp sensor the right reading and will also cause this problem.

Customer: replied 6 years ago.

explain more about the engine coolant temp sensor. where is it located? is it different than the thermostat. will the engine coolant temp sensor cause the cooling fans to

not come on even when engine is overheating? how hard is it to change for someone who knows very little?

Expert:  Amedee replied 6 years ago.

YES! This sensor is very easy to replace!


The engine coolant temperature sensor is a variable resistor with a range of -40°C to 129°C (-40°F to 265°F) .

The engine coolant temperature sensor provides an input voltage to the PCM. As coolant temperature varies, the sensor resistance changes resulting in a different input voltage to the PCM.

When the engine is cold, the PCM will demand slightly richer air/fuel mixtures and higher idle speeds until normal operating temperatures are reached.

The engine coolant sensor is also used for cooling fan control.


The sensor is installed next to the thermostat housing.



Customer: replied 6 years ago.
are there any other components that can cause this problem? is it true that the computer actually controls cooling fan speeds?
Expert:  Amedee replied 6 years ago.

You bet it is!


SOmetimes the cooling fan relay goes bad too causing this problem. But if you already replace it, it should not be your problem.

Edited by AMEDEE on 6/17/2010 at 2:23 AM EST
Customer: replied 6 years ago.
already replaced cooling fan relay. that's the first we did. when that didn't fix the overheating problem, the mechanic said the only thing else to do is replace the computer...maybe not the best advice...your opinion
Expert:  Amedee replied 6 years ago.

Yeah... that very bad advice. The computer only gets replaced as a last resort! Everything else i the circuit must be checked. Your mechanic either did not know what he was talking about or did not care because he was not paid a diagnostic fee to figure it out.



Customer: replied 6 years ago.

gonna give the engine coolant temp sensor a shot. the reason this is very important

to my wife and i is because we have a 13 yr old son who is profoundly disabled(mental retardation, blind, orthopedic disabilities). i don't want to see my wife stuck on the side of the road in 100 degree heat with my son in his wheelchair. i need to get this fixed

to relieve the stress of driving than van and not knowing if it will overheat. thanks for the advice

Expert:  Amedee replied 6 years ago.

You bet!


I hope this helps! Please don't forget to hit the "accept" button if you have found my answer helpful. You can always accept my answer now, and repost back again later on if you have any more questions. If you want to discuss it some more just hit "reply", it's free to do so otherwise don't forget to hit "accept" and leave positive feedback if you found my answer helpful.






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