C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Engine Temp. Switch?

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Old 05-06-2018, 08:10 PM
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procketus
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Default Engine Temp. Switch?

Yesterday headed to a show, about a 50 mile trip, the service engine soon light came on. Car still ran fine. I was watching the temp gauge, the digital one and it was normal. When we left the show the fans kicked on but the temp was still pretty low, around 150, at the same time the light came on.

Today, did the same thing. Fans on whenever it feels like with the light coming on. I needed to change the oil. When I got that done I fired it up and let it idle until the temp got up to around 220 and the light and fans came on. Cooled right down to 190 pretty quickly.

No codes coming from the computer.

Could the temperature switch be going bad on it?

The one on the water pump?

It's a '95 LT1 with a six speed.
Old 05-07-2018, 08:22 AM
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Whaleman
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I know the policy with the experts on this site is to NOT throw parts in without spending hours confirming the part is crap. This sensor is so cheap and easy to replace I would just replace it. But that is just me. Someone will jump in and tell you how to test. Dan
Old 05-07-2018, 08:31 AM
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C409
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..... Recheck for codes ... when the fans and SES light come on at the same time it is because the ECM is in limp home mode ... it has a reason for this that should show up in stored codes ... beg borrow or steal a real scanner .....
Old 05-07-2018, 09:14 AM
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WVZR-1
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If you had SES you have codes. If the SES has gone away then there'll be a HISTORY code. If you've very erratic coolant temps from the LCD in the cluster then you'd expect likely a DTC 14 or 15.

How did you determine there were NO CODES from the PCM?

The scanner check is ideal - don't throw parts. An ECT connector failure is maybe as likely as an ECT sensor failure if in fact you've got ECT CODES

CHECK CODES!!!

Do you know how to check codes using the DIC? Do you have the FSM?
Old 05-07-2018, 06:21 PM
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procketus
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Originally Posted by WVZR-1
If you had SES you have codes. If the SES has gone away then there'll be a HISTORY code. If you've very erratic coolant temps from the LCD in the cluster then you'd expect likely a DTC 14 or 15.

How did you determine there were NO CODES from the PCM?

The scanner check is ideal - don't throw parts. An ECT connector failure is maybe as likely as an ECT sensor failure if in fact you've got ECT CODES

CHECK CODES!!!

Do you know how to check codes using the DIC? Do you have the FSM?
I checked codes by jumping the #4 and #12 terminals in the plug.

Wife ran the car today and it did the same thing. Took it to where our son works and they could not pull a code because she shut it off and the light was not on. Temps were normal 195-200.

Went back out and rechecked. Am now getting a H27 code. That's in the history? From what I can tell online it points to the EGR.

Nope I don't have a FSM.....yet.

Thanks.
Old 05-21-2018, 01:30 PM
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65GGvert
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Don't forget the DVD service manuals I sent with the car.

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