96 Cadillac Deville Security Light On, Won't Start - After Fuel Pump Went Bad and Was Replaced

20

Asked by Jim Dec 04, 2017 at 09:54 AM about the 1996 Cadillac DeVille Concours Sedan FWD

Question type: Maintenance & Repair

96 Cadillac Deville Security Light On, Won't Start - After Fuel Pump Went
Bad and Was Replaced

Hello,

My 1996 Cadillac Deville has had hard first starts for a while.  I didn't think
much of it because after getting is started, it ran fine and starts for the rest of
the day were normal.  Then, on a the way home from work, the gas gauge
started reading incorrectly, then went totally empty even though I knew it was
at least half full.  

I searched the internet and found that I most likely had a bad fuel pump.  It
still drove fine, so I went to the auto parts store to get the pump and had to
get towed home because it would not re-start when I tried to leave.  When I
put the key in and tried to start the car, all the dash lights went out and the
yellow security light came on.

I previously read about the little VAT wires being a problem, so I picked up a
new ignition switch and changed the pump and switch out.  The little wires in
the pump assembly were melted.  The first few inches of the harness
(outside the gas tank) looked fine, so after replacing the pump assembly with
a new one, I put it all together.

When I took the steering column apart, both wires looked intact, but since I
had all the parts, I replaced the switch anyway.  After putting it all together,
reconnecting the battery, and trying to start the car, I am still getting the
security light and the car will not start.

The switch came with new keys, so I checked the resistance of the chip in
the new key and it was identical to the resistance in the old one (.889 ohms).  
I then disconnected the steering column wire harness under the dash and
checked to see that the I installed the switch properly and when I insert the
key, I I get a reading of .887 ohms.

I tried to read the codes from the computer with my code reader...because
the dash is blank...and only see one code: P0603.  I think everything has
been erased because I had the battery disconnected for about a week.  

My question is this:  

1.  Could the difference of .002 ohms be enough engage the security and not
allow the vehicle to start?  
2.  Did the fuel pump short out the VAT computer?
3.  Or, could another part of the wire harness be melted and how would I find
out where?

I'm an amature mechanic and anything I know, I've found on the internet.  
Unfortunately, I've been unable to find anything similar to what I'm
experiencing.

James

1 Answer

20

Turns out the problem was a fuse labeled ignition relay.

2 people found this helpful.

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