P.a.t.s Issue

[Taker730444]

Ok just bought a 96 gt. Battery was dead recharged battery and went to start it and nothing. I did notice something odd. When I turn the ignition on the theft light lights up then shuts off like it should. But when I crank the engine for about 3 secs the theft light starts flashing fast then continues to flash. So I turn the key off and it acts normal again till I go to crank it. Any ideas where to start? And it seemd odd it dont start flashing till I try to crank it over.

The battery was completely dead and it has been sitting for about a year.

 

[wmburns]

Turn the key to run but do not crank. Does the theft light go out after a 3 second "prove out"? If so then the PATS key has been read and accepted.

My vote is that you still have a battery problem. IE the battery voltage is not remaining high enough for the PCM to work during cranking. What is the voltage at the battery during cranking?

IMO every possible electrical problem should BEGIN with a through review of the battery and charging system. Don't let something as low tech as a battery be key to any project.

Here's some more information to review.

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


1996+ Crank with no start check list
http://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html#2984838

 

[Taker730444]

Key on no crank light does go off after 3 sec.

Takeing battery to be tested this morning.

 

[Taker730444]

went out to pull the battery and found these two wires that appear to be possibly grounds. They come from a round connector that is under the fuse box next to the battery. Any idea what they are and where they go?

 

[Taker730444]

I got a closer look at the wires under the fuse box one appears to be black with a white stripe and the other appears to be black with a yellow stripe that's before the connector. After the connector they both go to larger black wires that I'm holding in my hand in the picture.

 

[wmburns]

The round connector with the large black wire carry the CCRM and PCM grounds. These grounds are CRITICAL to the operation of the car's electrical system. A poor CCRM/PCM ground could absolutely cause the posted symptoms.

The Mustang has a ground system that bonds the battery negative to the radiator core support together. This in turn then goes to the round connector. From there onto the PCM and CCRM.

If asked to guess, the missing wires are part of the radiator core support ground.

The Mustang has used the same grounding system from 1996 through 2004. Do you have a buddy's Mustang to look at? Or how about a salvage yard in your area?

Another option is to look at the Ford wiring diagrams. If interested in getting a copy for yourself I maybe able to help. PM if interested.