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Discussion Starter · #1 ·
I have a 94 GMC Jimmy 4.3L, this is the problem: If I start the engine when it is cold, the digital dash shows the water temp as overheating. Would this be a colant temp sensor issue?

Chuck B.
 

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Try disconnecting the temperature sender,and see if it stops.If it does,it is most likely a bad sending unit.

If not,check for a grounded sending unit wire.If that looks OK,it may be the dash unit that has gone bad.
 

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Discussion Starter · #3 ·
Ok - help me out again. There are two colant temp sensors on this truck, yes. Where are they located.

Chuck B.
 

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The sensor for the dash gauge should be in the left side (drivers side) cylinder head,between the first two cylinders.
 

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Discussion Starter · #5 ·
Chris - when you say sending unit, you are refering to the sensor, correct?

Chuck B.
 

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Sending unit,or sensor,they are basically the same thing,just different terminology.

When you get a new one,make sure it's for the temperature gauge and not the CTS,or Coolant temperature sensor for the computer.
 

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Discussion Starter · #7 ·
I will check the temperature sensor like you suggested. If it is bad I will replace the CTS and this sensor. If it is good, I will change the CTS only.

Thanks for your help.

Chuck B.
 

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Do you know if the CTS is bad ? A good scanner would tell you quite easily.I wouldn't just replace it unless you've verified it's operating out of spec.
 

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Discussion Starter · #9 ·
Where can I get an adapter to fit my 94 Jimmy. I have a Snap-on Micro-scan, but it only fits newer cars!

The Snap-on guy will take a long time to get a hold of.

Chuck B.
 

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Discussion Starter · #10 ·
Chris - I unplugged the sensor between #4 & #6 cyl. and it still did the same thing. Only difference is that the check engine light came on the second I unplugged the sensor.

Chuck B.
 

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Maybe it is backwards on your truck,and you unplugged the CTS.I'm at home,so I can pull up any info here,but as soon as i get back in the shop,i'll let you know.
 

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Discussion Starter · #12 ·
I unplugged the sensor that is between the #1 and #3 cyl. When i started the car no reading is shown on the dash. So this must be the temp sensor.

Does the temp sensor have any input to the computer of the car, or is it strictly for temp readout?

Chuck B.
 

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Yes,that would be the temp sender for the dash gauge.It is not related to the computer at all,that's what the CTS is for.
 

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Discussion Starter · #14 ·
So temp sensor is bad, which means a trip to the dealer!

Chuck B.
 

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Discussion Starter · #15 ·
Chris, thanks for the help. The new temp sensor did the trick.

Chuck B.
 
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