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Ignition system fried. Jumper cable mix-up

I have a truck I keep for work around the house, hauling stuff and such and because a man is supposed to have a truck, right? Well, it sits unused a lot and, as it will happen, the battery gave up the ghost. I had been jump starting it to do things that could be done without shutting off the motor. I am a member of the West Virginia Air National Guard and had an item I needed to drop off to a fellow airman so I needed the truck for a day. I decided to charge the battery while at work and drive it in the afternoon to a battery store to replace the battery on site saving myself the trip to return the core. That was mistake number one. I work in Washington D.C. an hour and a half from my home in rural West Virginia. At 4:30 AM I pulled my Toyota Matrix up to my Ford Ranger and hooked up the jumper cables. This should have been done with the aid of a flashlight but, I believed I knew my battery pretty well having jumped it so many times. It didn?t help that when I bought the truck used it was missing that rubber boot that is usually on the positive side of the battery. You have probably already guessed that I put the cables on the wrong post. As you know this is what is known as a ?bad idea?. As you also know it sent voltage through my trucks circuits in the wrong direction. You further understand that this negatively impacts a vehicles electrical system. There was a pop and a sizzle and then only my angry utterances as I told the darkened world exactly what I thought of my intelligence and, unfairly, what a piece of $#%& my truck was. So 1990 Ford Ranger 4.0L V6 four wheel drive Manley truck sits waiting for my afore mentioned intellect to improve. So far it is still waiting. Here is what I know; 550 cranking amps will blow two 60A alternator fuses $6.00 total. It will also fry your starter relay $15.00. Now I have crank but it is still not start. I have exhausted the cheap easy to fix parts and am down to two maybe three possibilities. 1) A fusible link. I would love this to be the trouble it would be the cheapest but I cannot find a link anywhere. 2) The electronic coil pack $98-$130. This engine has no distributor just a computer a coil pack and cam and crank position indicators. 3) The computer $100 plus shipping. I just do not know how to figure out what to replace. I am familiar with the replace them one at a time till it works philosophy and if it were not my money I would do just that. The system takes and OBE-1 reader that I do not have and cannot drive the truck to so that?s out. I have disconnected the coil and ran a continuity check to one plug across all the pins on the input with no continuity showing at all. This may mean nothing or it could be that my coil is shot. I am stuck what should I do? I figure if I have to tow it for $50 and pay $60 an hour to work on it plus parts of at least $100 I might as well start buying and trying myself.

the fusible link is between the positive terminal and the main fuse box or maybe in the box itself…years ago someone jumped my car incorrectly and there was a popping sound as the link blew…

In regards to fusible links my ARRC data base states “Fusible links are located near the starter solenoid and shares the terminal with the battery-to-starter solenoid cable”.

Vehicle I checked on was a 1990 FORD Ranger 4.0

So since I have crank from the starter can I eliminate a fusible link? That takes me to my coil pack or computer. How do I check continuity on a coil pack?


I would not make that conclusion,the fusible links dont carry the load that turns the starter they provide a path from the main bus point on the solenoid out to other areas of the system. You still need to verify the condition of these fusible links.

Check that the coil packs have the proper DC voltages (most likely battery voltage) and you can check the coils for continuity with a ohm meter I dont have a figure for a FORD but I will see if I can get a figure on a GM coil (I am a GM man mainly but I drive a FORD,go figure).Perhaps I can find a FORD value

If possible use your nose to sniff around for that unmistakable smell of burned electronics. A good visual inspection may pay off also,just look at everything electrical (OK not the washer pump)under the hood,looking for damage.

I think I speak for all on the Forum when I say that we all appreciate what our men in uniform do for us, no matter what job they actually do.

OK like I said I am not a FORD guy but I see technical data for Dura Spark 2,Distributor ignition and Distributor less ignition. I will give a spec for coil testing.
Primary resistance check,between the plus and minus terminal of the coil between 0.3 ohms and 1.0 ohms no more no less.
Secondary resistance check,between the negative terminal on the coil and the high voltage terminal not less than 6500 ohms and not more that 11,500 ohms.
There is a ignition control module used and it is possible you may have to verify its condition.
I just don’t know these FORD ignition systems well.

If this data does not fit what you have tell me more about what type of ignition system you have and I will look. I have a online data base (ARRC) to look in and it is free for me.

My truck does not have a distibutor and coil set up it has a computer a coil unit that has 6 spark plug wires comming out of it and crank and cam position sensors.

I pulled the 4 prong plug off the coil and checked continuity to one plug wire across all the pins and got nothing. This could mean no continuity or that this is simply not the way to determine continuity.


OK went back and found distributorless ignition and the 4 pin connector,here is the data.
Terminal 3 (coil 1) plugs 1 and 5
Terminal 2 (coil 3) plugs 2 and 6
Terminal 1 (coil 2) plugs 3 and 4
Measure from terminal to high voltage terminal and suprisingly the spec is the same from 6500 ohms and 11,500 ohms.
You certainly seem to have confirmed a open coil as you should have seen resistance between 6500 ohms and 11,500 ohms from the high voltage output for plug 4 and terminal 1.
Just curious do you show battery voltage at terminal 4? you should have

These wiring diagrams, from show you the fuses, wiring, and wire colors, to do the circuit checks: You’ll have to “register” at that site, come back here, and click the link, again. Go down to Fig. 31, 32, 33, and 34.
There are, also, repair articles at that site, such as this ignition coil test: