Replaced Heater Core, Now Anti Theft Is On

Dec 15, 2017
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I replaced my heater core a few days ago on my 99 GT. After putting it back together and dash back in it ran good for a day with the exception of feeling like it was accelerating differently on release of the clutch. Thought I was was paranoid and tired. The following day I started it to warm it up and after about 2 minutes it died. I tried to start it again and the anti theft light came on and the module in the passenger fender well began buzzing with the key in the on position. Does anyone have any ideas before I take the dash back out? I fear maybe I possibly overlooked a connection on the wiring harness somewhere but was pretty confident I got them all. Any help would be greatly appreciated!
 
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wmburns

SN Certified Technician
Aug 14, 2009
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Yes. Check the ground to the CCRM. Especially the black wire with a white stripe that goes around the battery from radiator core support grounds.

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

The Clicking/buzzing CCRM is a HUGE clue. It either means:
  • CCRM ground is bad
  • The ignition switch is not making good contact. Check voltage out of fuse F2.34
  • The CCRM is bad. Seems unlikely to me as it worked before the work was done.
It would help to know the voltage status of some key fuses. Namely F2.34, F2.2 and F2.8.

IF F2.34 does not have voltage suspect an ignition switch problem.

IF F2.2 and F2.8 are pulsing with the CCRM, this all but "proves" the CCRM is at the root of the problem.

1999-2004 BJB CJB fuse panel layout:
http://www.allfordmustangs.com/foru...r-swap-wont-fire-please-help.html#post2669271
 
Last edited:
Dec 15, 2017
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I followed your advice and checked fuse 2.34 and wasn’t getting any power to it so I concluded it was the ignition switch. I pulled the steering column out with the fuse still pulled and and didn’t find anything visibly loose but I put it all back together and the theft light was out and it fired right up.. I’m a little confused as to what the issue really was but I can only assume one of the connections wasn’t making good contact.
I can’t thank you enough for your advice and you saved me from taking it to a mechanic.
Thanks so much #wmburns you’re the man!
 
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wmburns

SN Certified Technician
Aug 14, 2009
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PLEASE HELP ME!!!
I replaced the radio in my 2000 Mustang, and my Anti theft has come on and now my Car will not start, I have unhooked my battery, checked all my fuses, locked and unlocked doors.
There are tons of great tests in this thread. It would help if you also followed some of the great suggestions already given.

HOW have you "checked" the fuses? Does that include the fuses in the BJB=F1 and CJB=F2? For example. What are the results of the fuse F2.34, F2.2 and F2.8 test?

There is a ground behind the center console that is shared with many devices including the cluster AND the radio. It is frequently messed up during a radio install. The ground is actually multiple black wires all coming together in the same spot. Double check that non of the black wires were disconnected/broken during the radio install.

What about the check mentioned in the crank with no start check list of the CCRM/PCM ground? Which is the black wire with white stripe near the battery towards the radiator core support.
 

Neuron

5 Year Member
Nov 6, 2016
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PLEASE HELP ME!!!
I replaced the radio in my 2000 Mustang, and my Anti theft has come on and now my Car will not start, I have unhooked my battery, checked all my fuses, locked and unlocked doors.

FYI-The usual etiquette is to start a new thread with your problem instead of piggybacking on to another OP's.
Welcome to the Forum, this a good one.