99 GT Cooling fan runs when car is cold and key is off

[Karla]

The problem started when my 99 GT cooling fan was running when the car was cold and the key was off. I believe it is in the fail safe mode. Now it will not crank. The battery is fully charged. How do I test the fail safe mode for the cooling fan? Also, any ideas on what could be going on...

 

[wmburns]

It would also be handy to mention any "other" problems you may have. For example:

• Is this a "crank with no start" or a "no crank" problem? It makes a difference.
• Does the dash display all dashes? ("-------")
• Does the theft light flash or on solid?
• Does the battery run down over night?
• Are there any lights on cluster when the key is out?

Regarding your question about the fail safe cooling. Consider it would be EXPECTED for the cooling fan to run IF the PCM is not being powered. Just as the PATS system will not "prove out" if the PCM isn't being powered.

Is there key off power in fuse F2.34?

1996+ Crank with no start check list
https://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

1999-2004 MY fuse panel schedule:
https://www.allfordmustangs.com/for...r-swap-wont-fire-please-help.html#post2669271

 

[Karla]

It would also be handy to mention any "other" problems you may have. For example:

• Is this a "crank with no start" or a "no crank" problem? It makes a difference.
• Does the dash display all dashes? ("-------")
• Does the theft light flash or on solid?
• Does the battery run down over night?
• Are there any lights on cluster when the key is out?

Regarding your question about the fail safe cooling. Consider it would be EXPECTED for the cooling fan to run IF the PCM is not being powered. Just as the PATS system will not "prove out" if the PCM isn't being powered.

Is there key off power in fuse F2.34?

1996+ Crank with no start check list
https://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

1999-2004 MY fuse panel schedule:
https://www.allfordmustangs.com/for...r-swap-wont-fire-please-help.html#post2669271

Sorry for the omissions...this is my first time to post.

The car will not crank nor turn over at all. The theft light is blinking intermittently now but didn't at first.

The very first thing I noticed was that the battery kept running damn. I happened to be in the garage one evening and hearts cooling fan running when the car has not been trying for a couple of days. So I figured that cooling fan running was causing the battery drain. I did some reading and found out that the cooling fan running like this was because it was running in failsafe mode. I have checked all of the fuses with a meter and they are all good. Are red somewhere this same problem happened to another mustang because of a maintenance battery that I caused a short and some wires under the battery. They also said the theft system and Pat's system was a secondary issue that would clear up what's the and the short fixed. I hope this provides some information that helps.

 

[Karla]

There is a no crank problem
The dash does not display any dashes
The theft light flashes on and off
there are no lights on in the cluster when the key is out

 

[Karla]

I will go through the items that you listed and see how I come out with those and I will let you know. Thank you

 

[wmburns]

For a no crank problem:

• Confirm there is key on power in fuse F2.6
• What have you done to rule out a problem in the neutral safety switch (NSS)?
• What happens if the starter solenoid is jumped? Note this should make the starter engage. Make sure it's in neutral or park with the parking brake set.
• Can you hear the starter relay click in the battery junction box when the ignition key is turned to start?

I really suspect that your problem is a bad ignition switch. The ignition switch is powering the car's electrical even though it's off. At other times it's not powering all of the circuits that the car needs to run.

The ignition switch can be replaced by a DIY'er and does NOT require PATS reprogramming or a new key cylinder.