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There was a time.....when people were selling diagnostic BBs. Actually they were selling 'performance chips' on eBay etc to enhance the performance. In reality....they were a radio shack resistor wired into the coolant sensor.

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50 minutes ago, Jeffery said:

Could it be possible someone went into computer and messed something up to get this false readings  ?

Have you done the tests?  Do you know how to get into the diagnostics to read the real time data?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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7 minutes ago, Jeffery said:

I know how to check for codes that's it but have not had time to check readings yet 

Ok, first, I do not believe that its possible to override the temperature in the diagnostics.

The diagnostic tree that I gave you above requires that you get into the diagnostic to read real time data at PD04.

I will post how to get into the diagnostics its different than checking the codes. 

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Here is the diagnostics information, see the top of pages 12 and 13 for the diagnostic menu structure.   When you run codes, I am sure you have seen, PCM?, when you get to the end. 

At that point you have the option of pressing the LO fan repeatedly to toggle through the following categories:

  1. PCM DATA?
  2. PCM INPUTS?
  3. PCM OUTPUTS?
  4. PCM OVERRIDE?
  5. PCM CLEAR CODES?
  6. PCM SNAPSHOT?
  7. hitting LO again will cycle you back to #1 PCM DATA again

You can see this at the top of the page 12 and 13, from left to right looping back to the beginning, print or download these pages to see them better.

Now, based on the diagnostic tree I gave you earlier in this thread, you want to observe PCM DATA at PARAMETER NUMBER PD04 - Engine Coolant Temperature and compare the readings to what is in the tree above.  

When you see PCM DATA?, hit the HI fan button, and you will get into the PCM DATA parameters that range from PD01 through PD99, see page 12.

Once you are in PCM DATA, you will be in PD01, you want to get into PD04, so hit the LO FAN button again to toggle through the parameters till you get to PD04.   In the chart you will note that the range is -40 to 151 degrees C.    You can observe this parameter as the engine warms up, get into the parameter when the engine is cold and keep an eye on it, plus you can do the tests above. 

By the way, this is the way you should delete codes, by going to #5 and clearing codes.    Remember LO is NO, and HI is yes. Hitting OFF on the HVAC control will back you out of each menu.  When you get back to PCM?, turn the key off.

Don't go into the PCM OVERRIDE area, I am not sure how easy it is to accidently override a parameter but don't want to take the chance.   If you enjoy this sort of stuff, pick up the factory service manual on ebay, I go to bed with it, the learning never stops....haha   :blink:   I am curious what your problem is.  Keep in mind that the ECT sensor is also connected to the PCM and there is a connector at the PCM that can cause problems also.   I need to find out where the PCM is in your 94, you should do a tap test on the PCM also to see if it affects the PD04 parameter.   Let us know how it goes.

Page 12 and Page 13 sit side by side in the manual and are a continuation of each other,

OBD1%20diagnostic%20commands0001a_zpsuer

OBD1%20diagnostic%20commands0002a_zpsujk

OBD1%20diagnostic%20commands0003a_zpsnog

OBD1%20diagnostic%20commands0004a_zpsl1c

 

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Ok ohm test on sensor shows sensor to be good leveled out at around 212 degrees f  . I drove down rd and got same stop engine message I got back and ohm tested again it showed 212 again so sensor is good . either connector is bad or I have other shorted wires elsewhere. What should I check next ?

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You have to check all connectors and the sensors first.  Let me know what you find.  I did more reading and know the ECT pins on the PCM.  Sometimes resetting the connectors on the PCM will reset them.  You have 3 plugs on your PCM.  The RED and WHITE connectors involve the ECT sensor at 1B5 and 2C1 the sensor return.

The PCM is located on the passenger side facing the wheel well.  You may need to peel back /remove carpet and covers to get at it.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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21 hours ago, Jeffery said:

I'll check connectors next thanks 

I want you.to consider something.  When the engine is cold 5 volts is detected.  When the engine is hot, no voltage flows.  An intermittant bad connection will mimick, no voltage flowing........and indicate HOT

Peel back the carpet and wiggle the red and white connectors while watching the temp..    Then with your knuckle, tap on the PCM and see if the digital readout for temp changes

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Keep an eye on it, see if the stop engine happens at the same temp, 160 every time.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Not every time but temp will jump all over place until it gets high enough for computer to say it's to hot and to shut it off. do you think computer has went bad I don't know what else to do 

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You need to determine if its the sensor or the wiring.  

Rockauto has an ac delco sensor for $21.  

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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3 minutes ago, Jeffery said:

Not every time but temp will jump all over place until it gets high enough for computer to say it's to hot and to shut it off. do you think computer has went bad I don't know what else to do 

You need to read the voltage when its jumping all over.  Does it jump all over when you sit still and warming up or just when you are moving?

Did you uncover the PCM and tap on it?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I would like to hold off blaming the PCM till we are sure

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Just now, Jeffery said:

I forgot tap test I'll try that and get back to you 

Ok good, have fun

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 6 months later...
27 minutes ago, Jeffery said:

wanted to update turned to be computer was bad thanks for all the help

@Jeffery thank you for the update

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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