50Amp Ign Pops
Fergie,
Now I think I get it. One last time: No key in the ignition, the link will last for
5 to 8 seconds before it blows? Assuming that is the case, suggest you start
eliminating branches of the circuit tree that relate the the starting diagrams in the
previous links. Let the fuel pump rest, it is powered by another source and is
most likely ok. Your problem is most likely in the Engine Compartment Junction
Block, there may be an internal short in that box. I haven't torn into that box, but
recently one of the forum members did an R&R on his due to internal short. It
was a post within the past month, he could see the underside damage to the
block. I have attached a file that will show you what the top and bottom look
like. One quick test would be to pull the start relay and see if a link still blows
after the 8 seconds. If the relay has an internal short, it would be good to know
before you move to the test that follows. If the start relay removal still allows the
link to blow, perform the following test:
Disconnect the negative battery lead.
Focus on the E/R-B socket on the bottom, disconnect it, if you do not see
visible damage, leave that connector off, reconnect the negative battery lead
and put in another link to see if it still blows.
If it blows, the problem is in the box, if not, it is in the connector and harness that
plug into the E/R-B socket. Once results are known from that test, you can
replace the Junction Block or chase the shorted wire(s) in the harness and
connector. I will research the 8 pins on the E/R-B connector to see what the
likely shorted item(s) might be.
The reason the car stops running after a few seconds is due to the loss of power
to the PCM, specifically the "On" voltage that would be the input to tell the PCM
the ignition switch is either on or in the start position. Without that voltage it
thinks the key has been turned off and shuts all engine operations down. The
voltage is provided by fuse 25 in the passenger compartment fuse panel. It is
also a supply voltage for the Ignition Failure Sensor, another PCM input that
is used to determine if the engine is running. This problem is rare and most
unfortunate. If you can dig into the fuel pump you can tackle this one, just watch
for obvious heating due to high current flow. You might let this post sit for a while
until others who may have dealt with similar issues have weighed in. Do not
despair, you can and will find this gremlin.
Paul