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98 Ford Crown Vic P71 Interceptor wild electrical problem
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mr_notorius5500
New User
May 31, 2009, 1:01 PM
Post #1 of 6
(7519 views)
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98 Ford Crown Vic P71 Interceptor wild electrical problem
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My 98 Crown Vic Police Interceptor with the 4.6 V8 engine and 153k miles has developed a peculiar and daunting electrical problem that has me completely stumped. I went to start the car one morning and it wouldn't fire up, but I immediately discovered it was because the fuel pump wasn't kicking on. So I checked the fuse and pump relay, both check out good and then I tried jumping the power side of where the relay plugs in and the fuel pump kicked on. So then I used my voltmeter to probe the control side and discovered that there was no voltage going through the circuit whatsoever. Then I started checking connectors on the wiring harness. One connector I moved around suddenly caused the circuit to spring to life and at that point I believed all I had was a short somewhere in the harness. I plugged the relay back in and successfully got the engine to start, but as I closed the hood, the engine died. I opened the hood, re-jiggled the connector, restarted the engine, then closed the hood again and the engine died again. So the third time I did all that again but I closed the hood gently and the engine stayed running, but then I climbed into the car and hit the brake, and the engine died yet again. I also noticed my gauge cluster completely went off as if I shut the car off (even though the key was on). I decided to start seeing what else contributed to these strange symptoms. Starting the engine, I tried playing with the few accessories the car had. I discovered that the power window master switch does the same thing to the car as hitting the brake, but the slave switches have no effect on the condition, and in the steering column, the hazard switch causes the chime module to buzz! I have a strong feeling that something went very wrong in the harness, but I'm not sure.
Among what I mentioned trying already I also started removing wire loom from the wiring harness to inspect the wiring and I discovered someone had jumped the EEC power and fuel pump relay power wires together. Since this is an old cop car, I thought it was something the police outfit did when they removed all their equipment, but now it seems that's not the case. I should also note that the week before, the car had a problem with the cooling fan not kicking on and the vehicle running hot. Through testing, I found the control side of the cooling fan relay was not supplying enough voltage to activate the relay, so I ran a new wire from the EEC relay to the fan relay and that took care of the problem, although I'm lead to believe that these problems and this entire electrical freakout problem are related somehow. I'm just not exactly sure what it is or where else to look. Any ideas? Anyone?
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Sidom
Veteran
/ Moderator
May 31, 2009, 1:18 PM
Post #2 of 6
(7512 views)
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Re: 98 Ford Crown Vic P71 Interceptor wild electrical problem
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Man sounds like you got a project on your hands..... Better you than me  j/k
Looks like you've aready found a few problem areas... You need to find out whats up with that connection you are wiggling. Inspect the wires & take the connection apart & do a pin drag test on the pins to make sure they aren't loose.
Those fuel pump & fan circuits with the rigged wires, they need to be traced down & find the problem. The only problem I have with running new power wires is.... what else in that harness where the original wire failed is going to go next? Voltage drop those circuits & find the problem
With the dash problems get a schematic & look for common grounds or power sources & start there, could be they're related.
Sound like you have a little work ahead of you... I don't envy you but from your post sound like you have the knowledge & tools to track it down
(This post was edited by Sidom on May 31, 2009, 1:21 PM)
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mr_notorius5500
New User
May 31, 2009, 9:56 PM
Post #3 of 6
(7491 views)
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Re: 98 Ford Crown Vic P71 Interceptor wild electrical problem
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Thanks for the tips man. Unfortunately I'm going out of town this week cuz of my job and I won't be able to tackle the car again till probably this weekend, but in that time, I know where I can get access to ShopKey software and pull up all the wiring schematics I can think of and study up while I'm gone . I'll leave a follow-up after I figure out the problem. Thanks again.
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way2old
Veteran
/ Moderator
Jun 1, 2009, 3:32 PM
Post #4 of 6
(7485 views)
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Re: 98 Ford Crown Vic P71 Interceptor wild electrical problem
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Look at the wiring loom under the right front(passenger side) bumper. These are bad about getting water in there and corroding wiring. It is between where it loops down and goes over the lower tray behind the bumper cover. Usually a brown wire or a green/red wire.
Being way2old is why I need help from younger minds
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mike1987
New User
Mar 20, 2011, 5:41 PM
Post #5 of 6
(6183 views)
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Re: 98 Ford Crown Vic P71 Interceptor wild electrical problem
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i think im having the same problem but when i step on the break it acts like its gonna shut off, when i do put it in gear it dose shut off. i was wondering if you found the problem? my dash aint working properly either
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zmame
Veteran
/ Moderator
Mar 20, 2011, 6:19 PM
Post #6 of 6
(6180 views)
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Re: 98 Ford Crown Vic P71 Interceptor wild electrical problem
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Thread is almost 2 years old if you have a question please start a new thread
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