battery hooked up backwards!

twistedturbine · Sep 29, 2007

My truck was parked at a buddys house, one of his friends borrowed the battery and hooked it up backwards when he put it back in. Truck is an 89 ranger 2.9l 4x4. It blew the 50 and 60 amp alt. fuses in the underhood fuse box and the starter relay. I replaced the fuses and the relay and the truck now turns over but has no fuel and no spark. Fuel pump runs constantly with key on and has fuel pressure. What else could have gotten fried that would cause the no spark/ no fuel condition. NO fuses in the cab were blown and all accesories work.

martin · Sep 30, 2007

What else could have gotten fried that would cause the no spark/ no fuel condition.

Anything that contains any electronics.

kunar · Sep 30, 2007

twistedturbine said:
the truck now turns over but has no fuel and no spark. Fuel pump runs constantly with key on and has fuel pressure.

i would check the computer. if its got fuel pressure but you say it doesnt have fuel...i take it the injectors dont fire? have you tried to pull codes?

twistedturbine · Sep 30, 2007

havn't tried to pull codes yet. if the computer is fried what would happen when I try? oh and the injectors don't fire. is there a way to check the ignition module?

MAKG · Sep 30, 2007

If the computer is fried, either you'll get codes or you'll get nothing at all. Depends on what part fried (it's not necessarily true that all of it fried).

The computer power distribution is NOT fried or your fuel pump would do nothing.

twistedturbine · Sep 30, 2007

can I use a digital multimeter to get the codes or do i need an analog one?

Bob Ayers · Sep 30, 2007

MAKG said:
If the computer is fried, either you'll get codes or you'll get nothing at all. Depends on what part fried (it's not necessarily true that all of it fried).

The computer power distribution is NOT fried or your fuel pump would do nothing.

If the fuel pump is running continuously with the key on, then the PCM is at fault. The fuel pump relay is picked via an open collector (or drain) driver in the PCM that grounds one side of the relay coil to close the relay.

MAKG · Sep 30, 2007

Bob, can we rule out a stuck fuel pump relay?

I'd try disconnecting the computer. Then, if turning the key on does nothing, it's almost certainly the computer. If it still runs, something else is at fault.

Bob Ayers · Sep 30, 2007

MAKG said:
Bob, can we rule out a stuck fuel pump relay?

I'd try disconnecting the computer. Then, if turning the key on does nothing, it's almost certainly the computer. If it still runs, something else is at fault.

Good idea!!

swamprat · Sep 30, 2007

I would have the guy that messed it up fix it. Then again if he dont know how to hook up a battery the you are better off doing it your self. Is there any fuseable links on that truck? Thought there is one by the alt.

Sasquatch_Ryda · Sep 30, 2007

Had an issue like this come into work once, it was an aerostar tho....ended up being a fusable link in the wiring comming off of the battery

twistedturbine · Oct 4, 2007

don't think there are any fusible links. It has the underhood fuse panel. The truck is like 2 hours away so i can't go look either. Do you guys think there is a good chance that the computer is screwed. Could the ignition module on the distributor have gotten messed up to? What controls the fuel injectors is it just the computer or does the ignition module have anything to do with triggering them? I'm trying to get an idea of what i'm gonna have to replace to get this truck going, before i drive back over there.

RobbieD · Oct 4, 2007

Was the ignition switch turned on during the time that the battery was reversed? The reason I ask, is that a lot more stuff was exposed to reversed polarity if the switch was cycled, than if it wasn't. Kind of sounds like it was, though.

And you're right; by '89 the underhood fuse box replaced fusible links. I'm sorry that I can't help you much here; I have never ran into a battery polarity reversal situation that was anything more than replacing blown fuses, links, or melted wires to get things back to normal. I've seen tons of individual radios, amps, control modules, etc. fried, but this is a different situation, being a battery reversal versus a component mis-wire. I simply don't know with any certainty what all could have been damaged here, in the individual systems and components.

If it helps (I hope it does, anyway), if I had to deal with this, I would get my hands on the Ford EVTM, or any wiring diagrams on that truck, and start checking all of the power circuits from the battery back to each problem component. For example, is each and every fuse actually passing power? Is the ECM getting power like it should? The coil and the ignition module? It's probably going to take a logical and methodical step-by-step tracing of the circuits back from the battery to sort this thing out. Sure was a pisser of an accident, and I wish you the best luck in getting it fixed.

fastford04 · Oct 5, 2007

sorry to say but ur buddy is a DUM ACE!! lol id make him fix it or make him pay to have it fixed if he messed it up!! lol thats just me tho!!

twistedturbine · Oct 6, 2007

the igniton switch was cycled. I tried the start it. I realized what was wrong when i looked under the hood to see what was wrong. Can anyone tell me what controls the injectors. If i turn the engine over they should spray fuel right? If the computer controls the injectors i'm going to replace the computer next timr i'm out that way and see if it works.

battery hooked up backwards!

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