Engine/Transmission (1998.5 - 2002) Engine Control Module. Electrical help

[R D Brown]

I am looking into installing an anti theft switch in the ground circuit for the Engine Control Module on my 98. 5. It has two ground wires, pin 30 and pin 49. I think one is a signal ground and the other is a power ground but don't know which one is the power ground. Does any one have the answer? Also would opening the ground circuit cause any problems other than the engine not starting? Thanks for any help.



RD B

 

[15w40]

I think it is a bad idea to break either of the ground connections for the anti-theft switch. The problems with a missing ground can over voltage some of the 5-volt sensors and the Central Timer Module. It may be a risky way to stop the truck from starting.



I found a good anti-theft circuit that has worked well for me for years. Instead of breaking the ground connection to the ECM, break the ignition on signal to the ECM on pin 5. This will allow the engine to crank normally but the ECM never gets the signal to inject fuel. I was able to find the wire in the under-hood Power Distribution Center (fuse box). I cut the wire where it enters the big 43-pin connector on the engine side of the fuse box. The pin number is 28 and the wire color is LG/BK, light green with a black tracer. Cutting the wire and running each side to a hidden switch will disable the truck with the switch open.

 

[R D Brown]

Thank you Dave, I'll give that a try.



RD B