Ignition Woes
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Senior User
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From: South Texas
There are two red/green wires going to the igntion module. From what I can gather one runs from the EEC relay to the module and one runs from the ignition switch to the module. I have 12 volts on the one that the test designates as the 'run' wire but none on the other 'start' wire. There is also voltage on both wires at the ignition coil. But no, my wiring diagram isn't detailed enough to show numbered splices. Any chance you could give me a description of whereabouts that splice might be, and what it would look like? Also, should I be looking for a wiring issue at this point?
I have another question that is slightly off topic. I've browsed the Helm website and am interested in the wiring diagram and/or shop manual. Does the more expensive shop manual include the wiring section, or does that have to be purchased seperately? I can't really afford either right now, but some more detailed info might be real handy in the future, as I plan on keeping this truck for a while. Assuming I can ever get it back on the road again.
I have another question that is slightly off topic. I've browsed the Helm website and am interested in the wiring diagram and/or shop manual. Does the more expensive shop manual include the wiring section, or does that have to be purchased seperately? I can't really afford either right now, but some more detailed info might be real handy in the future, as I plan on keeping this truck for a while. Assuming I can ever get it back on the road again.
Last edited by irishguyincc; Apr 21, 2006 at 01:32 AM.
Postmaster
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From: SoCal
Since you're seeing 12 volts at the ignition module & at the coil the wiring is OK.
The ignition module & EEC relay are not wired to each other, but both are wired to the computer/ECA.
Take a couple of minute to pull the trouble codes & post back with your results.
BTW, if the fuel pump runs the EEC relay is working.
A haynes manual will cover most things, but for electrical repairs the Ford "electrical & vacuum troubleshooting manual" is the ONLY way to go.
I have the EVTM for my 87 Ranger & 95 Taurus & they have saved me a lot of $$$ on electrical repairs.
The ignition module & EEC relay are not wired to each other, but both are wired to the computer/ECA.
Take a couple of minute to pull the trouble codes & post back with your results.
BTW, if the fuel pump runs the EEC relay is working.
A haynes manual will cover most things, but for electrical repairs the Ford "electrical & vacuum troubleshooting manual" is the ONLY way to go.
I have the EVTM for my 87 Ranger & 95 Taurus & they have saved me a lot of $$$ on electrical repairs.
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From: South Texas
I tried to check for trouble codes, but the computer would not go into test mode during KOEO. I have a tester and have done this many times before with no problems, but this time I get nothing. I tried it a few times, even replaced the battery in the tester with a new one. Still it would not enter test mode.
Does the engine have to be warm or have been started lately for the test to occur? Because obviously I can't do that. I'm pretty sure I've tested in the past without warming up and still was able to pull the codes. Am I having a computer problem? Any ideas would be appreciated, this problem just seems to get more and more confusing.
Does the engine have to be warm or have been started lately for the test to occur? Because obviously I can't do that. I'm pretty sure I've tested in the past without warming up and still was able to pull the codes. Am I having a computer problem? Any ideas would be appreciated, this problem just seems to get more and more confusing.
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From: South Texas
So odds are good I don't have a wiring issue? I'm just stumped as to why the computer isn't going into self-test mode, and why I can't see any voltage on the start wire going to the ignition module. And why did Ford use two red/green wires anyhow? Any ideas/suggestions would be very much appreciated.
Postmaster
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From: SoCal
Fuel pumps not running (in your previous thread) and no codes are a match.
See if you have power to the computer on the 2 solid red wires with the key on.
Computer is on the "lower right hand cowl."
See if you have power to the computer on the 2 solid red wires with the key on.
Computer is on the "lower right hand cowl."
Postmaster
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From: SoCal
Well, that explains why you cant pull any codes.
The EEC main relay controls the voltage to those red wires -pins 37 & 57 on the computer.
Check voltage at the relay if you have voltage on solid yellow from the fuse link & on red/light green from the ignition switch, but no voltage on the other 2 wires, replace the relay & fire this thing up.
BTW, that third red wire controls voltage to the WAC relay & turns off the AC compressor at full throttle.
The EEC main relay controls the voltage to those red wires -pins 37 & 57 on the computer.
Check voltage at the relay if you have voltage on solid yellow from the fuse link & on red/light green from the ignition switch, but no voltage on the other 2 wires, replace the relay & fire this thing up.
BTW, that third red wire controls voltage to the WAC relay & turns off the AC compressor at full throttle.
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From: South Texas
I checked the wires and there is not voltage on the yellow wire. The red/green wire does have voltage. I also checked the yellow wire that goes to the fuel pump relay, and that one does have voltage. It looks like both yellow wires splice into another wire and employ fusible links. I'd check the other side of the link, but I can't seem to find it. Is this likely where my problem is? If so, could you point me to the right spot to look? And thanks for getting me this far, I do appreciate it.
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Postmaster
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From: SoCal
The fuse links connect to the starter relay.
Grab the red fuse link on both ends, if you can stretch it its blown & theres a short between the fuse link and EEC relay.
Looks like your making some good progress here, might have this thing running before too much longer.
Grab the red fuse link on both ends, if you can stretch it its blown & theres a short between the fuse link and EEC relay.
Looks like your making some good progress here, might have this thing running before too much longer.
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From: South Texas
Thanks for that info. I checked it out and the link is fine. I also checked the yellow wire were it starts at the link and there was power there. So there is power at the one end of the wire but it's not making its way to the relay. It looks like most the wire is in a very tightly wrapped section of the harness. The end of the wire at the relay plug is exposed though. I wouldn't think that the wire would be messed up inside that harness as it can't move, but I guess anything is possible. What should I do now?
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From: South Texas
I'm just perplexed as to how a wire could break in there, it looks quite tight and the harness is secured to the fenderwall. Especially since all the truck did was sit for a week. Do you think I should tear it apart or just run a new wire?
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Senior User
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From: South Texas
I decided to remove the air box and open up the harness to get a better look. First off
let me say that Ford used too many yellow wires. Once I opened things up I found three. With this better view I did find a bad fusible link. The one I was probing was actually the one for the fuel pump. It's confusing having two blue wires and three yellow wires. I checked out the entire length of the yellow ECU wire and it looks good. The only exposed area is actually at the relay plug. Perhaps this exposed area touched the wire next to it and grounded out?
I know I need to replace the link but don't know how. My Chilton's has a vague picture showing the process, but it isn't very helpful. Could someone tell me how to do this?
let me say that Ford used too many yellow wires. Once I opened things up I found three. With this better view I did find a bad fusible link. The one I was probing was actually the one for the fuel pump. It's confusing having two blue wires and three yellow wires. I checked out the entire length of the yellow ECU wire and it looks good. The only exposed area is actually at the relay plug. Perhaps this exposed area touched the wire next to it and grounded out?
I know I need to replace the link but don't know how. My Chilton's has a vague picture showing the process, but it isn't very helpful. Could someone tell me how to do this?
Cargo Master
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You need to find the short that caused the fusible link to blow. The fix is to buy the right gage fusible wire, solder it in and shrink insulate the connection. if it has an eyelet then solder a new one on and shrink insulate it also.