A couple weeks ago I thought id be smart and wired the window lock switch as an immobilizer by isolating the switch and running the fuel pump power through it. Ran fine until a couple days ago when it died mid flight.

The 30amp ecm fuse was blown. Replaced fuse and it just kept blowing. I pulled the fuel pump and ran power to it and just an odd sound. Ie it was fried. Tested another one i had and put it in.

Wont start. Put my meter on the leads going to the pump. At ignition i can see the voltage go high for a moment then residual readings only.

Swapped the relays around for the fuel pump and ballast resistor to no avail.

Been looking at the wiring diagrams in how to by pass the ballast resitor circuit sucessfully. Cant see how to do that. Ideas?

From what i understand the ballast is used for typical use but goes out of line at start, WOT or certain loads. Is that right?

MY CPS and O2 sensor are new within last 2 years.

Ideas?

 

Is that window lock switch rated for that kind of load?

 

Ballast is fed from starter relay.....

 

The door locks are on a 30amp breaker the fuel pump on a 15 amp fuse. Thought it would be ok but i dunno. May be coincidence.

I should have mentioned i removed the switch and soldered the wire back. Possibly i had damaged another component in doing so.

Swapped out ECMs to no avail.

Its not popping fuses as i now think that was due to the shorted fuel pump.

When i sort pic 30 and 87 on the fuel pump relay i get nothing,

 

The O2 Sensor heating circuit was open. Off to get an new one when the ride arrives. on a 91 its fed from the 15amp ign circuit in the pwr dist blk and then through to the heated part of the O2 sensor where it completes the circuit to ground unless open.