Dash cluster not working and car will not start

BULLITT1939

MEMBER
2003 FORD MUSTANG
4.6L
V8
2WD
MANUAL
21,000 MILES

Saleen Mustang. Battery was dead. My husband said dash did something crazy before it went out. Replaced with brand new battery. Now dash cluster doesn’t really work. Occasionally gas gauge will work and mileage turns to dashes. It turns over, but will not start. I don’t hear fuel pump kicking on. The theft like blinks, but once I put key in on position it goes off. Scanners won’t connect says connection failure! No sure what else to check at this point!

5 Replies

BMDOUBLE

MECHANIC
1,139 POSTS

The dashes on the cluster indicate that the power train control module is not communicating with the instrument cluster, usually because the PCM power relay is not operating or possibly a bad ground connection amongst many other causes. Ensure that the battery cable terminals are clean and the cable is not swollen with corrosion. The instrument cluster could also be faulty, the anti theft system module is integral to the cluster but with no communication my first suspect would be the PCM relay or PCM. Being that this started out as a dead battery though I would really pay close attention to cable and terminal condition and grounds.

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Tuesday, April 16th, 2019 AT 6:37 PM

BULLITT1939

MEMBER
33 POSTS

I have taken terminals off and cleaned them well. Turn the key and abs and brake light come on temp then go off. No other lights or gauges are working. What should I check next? Battery is fully charged. Car turns over but won’t start.

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Wednesday, April 17th, 2019 AT 12:16 PM

KEN L

MASTER CERTIFIED MECHANIC
43,110 POSTS

Hello,

This sounds like a classic ignition switch issue. To be sure lets use this guide and the wiring diagrams below to test the connections for power:

https://www.2carpros.com/articles/how-to-check-wiring

Make sure the gray/yellow, red with light green and black with light green have power when the switch is on. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

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Friday, April 19th, 2019 AT 1:04 PM

BULLITT1939

MEMBER
33 POSTS

Ok so traced down a bad fuse F2 34. It is a 20 amp that keeps blowing. Also had a terrible hacked in alarm system which I had no remotes to. Changed the fuse then set the alarm off. Had to start dismantling the whole system. Once the alarm system was taken out I put another fuse in blew again. This fuse is controlling several things. I put a 30 amp fuse in just to see if any change and the car starts and runs fine. However, there is obviously a short somewhere I need to track down. Any suggestions?

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Sunday, April 21st, 2019 AT 8:35 PM

KEN L

MASTER CERTIFIED MECHANIC
43,110 POSTS

That fuse runs the cluster and ignition coil and a few other things. Here is a the wiring diagrams for that fuse so you can see how it works and what to disconnect to get the problem to go away. I would start with the ignition coil. Check out the diagrams (below). Please let us know what you find.

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