cant help much sorry
Ignition wiring trouble
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From: jax. florida
Ignition wiring trouble
I was fixing a broken wire to my ignition switch (yellow wire) on my 1990 F150
4.9 300 e4odtrans..I accidentally grounded out the wire and now it is dead....
I have no power at all going to it now....All fuses in the fuse box under the dash are fine......My headlights and horn work but nothing else, when I turn the key nothing at all happens....No radio, AC, nothing ...........I am in need of advice....My window is down and its is going to rain....PLEASE help me.....
4.9 300 e4odtrans..I accidentally grounded out the wire and now it is dead....
I have no power at all going to it now....All fuses in the fuse box under the dash are fine......My headlights and horn work but nothing else, when I turn the key nothing at all happens....No radio, AC, nothing ...........I am in need of advice....My window is down and its is going to rain....PLEASE help me.....
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Joined: Dec 2002
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From: USA
If your '90 truck is like my '92, there is a power distribution box under the hood on the driver's side, mounted on the inside fenderwell, just in front of and below the brake master cylinder. Open that box and there are 2 rows of fuses, large and small, and a row of relays. Starting with the Maxi fuses on the left side, check each fuse untill you find the one that's blown, and replace it with a fuse of the same amp rating.
For the rain, if you have a tarp, put it over the truck cab and tie it off
.
For the rain, if you have a tarp, put it over the truck cab and tie it off
.
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From: Langhorne, PA
The Haynes schematic for 90 91 F-series, shows that the yellow wire is the supply to the ignition switch. The switch controls the voltage to the variuos accesories, etc. The yellow wire has a fusible link between the switch and battery, Haynes simply says" "fusible Link BRN". I assume that means it is a brown color-coded fuse. I have no idea where that link is. The Haynes manual gives the actual Ford P/N's for several fusible links but doesn't mention a "Brown" link.
Look for a wire interuppted, the fusible link is simply a thinner gauge special wire that is designed to melt before the wire it protects can overheat and catch fire.
If you are a risk-taker and need to get moving, try installing a jumper wire from the battery to the igniton switch where the yellow wire is.
Look for a wire interuppted, the fusible link is simply a thinner gauge special wire that is designed to melt before the wire it protects can overheat and catch fire.
If you are a risk-taker and need to get moving, try installing a jumper wire from the battery to the igniton switch where the yellow wire is.
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From: Langhorne, PA
Try searching the electrical wiring forum if you get stuck, I did a search and found a couple items about the "yellow" wires, or "fusible links". There should be two thick yellow wires attached to one of the terminals of your starter relay. I am talking about the fender-mounted solenoid just behind the battery in the engine comp.
I ran outside and looked at my 92 truck, and indeed there were two thick gauge wires( might have been solid yellow) terminated with a ring terminal and bolted to the rear-most stud of the starter relay.
Both yellow wires were covered in heavy insulation and disappeared into the plastic covered harness and went down behind the battery tray.
The fusible link you need may be there, just a few inches away from the end of the two yellow wires.
I ran outside and looked at my 92 truck, and indeed there were two thick gauge wires( might have been solid yellow) terminated with a ring terminal and bolted to the rear-most stud of the starter relay.
Both yellow wires were covered in heavy insulation and disappeared into the plastic covered harness and went down behind the battery tray.
The fusible link you need may be there, just a few inches away from the end of the two yellow wires.
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From: jax. florida
Thank you for the help I know exactly where you are talking about...I will do the search also and hopefully find some more input to this problem....If that is where the link is blown do I need to replace it with the same kind of wire??? If so where do you get it from??
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From: Langhorne, PA
I would hope that a dealer has them in stock, but you should try your local shop first. I never changed one, the Haynes has two pages on how to install them, it seems easy enuf, but the critical part is getting the right size link for the application, If you start tearing into the harness, don't destroy any clues or color codes that identify the link. If the link is too small, the fuse will melt when you are far from home, if it is too big, you run the risk of melting the insulation anywhere along that circuit, which is very big trouble.
I hope you can find the link and confirm it is "open". Once that is settled your'e almost done. do you have a voltmeter/ohmmeter?
You could solder in/crimp in a temporary splice, if you are positive that there are no short circuits left at the igniton switch. Like I said, if you melt the insulation on that yellow wire feed, Murph's law states that it will be in the worst possible part of the wire.
I hope you can find the link and confirm it is "open". Once that is settled your'e almost done. do you have a voltmeter/ohmmeter?
You could solder in/crimp in a temporary splice, if you are positive that there are no short circuits left at the igniton switch. Like I said, if you melt the insulation on that yellow wire feed, Murph's law states that it will be in the worst possible part of the wire.
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From: Central NY
Yes you'll need to replace the link with the same amperage link. Think of it as a fuse. In fact, I've heard people using inline slo-blo fuses also but keep in mind that they will corrode faster than a new link. Links are sold at every autoparts store I've ever gone to, they are common in every make vehicle. All 924's precautionary statement apply in either case , fuse or link.
Verifying the link went open is easy, feel or look at it, If theres a bump - its open.
Best Wishes,
Popa Tim
Verifying the link went open is easy, feel or look at it, If theres a bump - its open.
Best Wishes,
Popa Tim
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From: SC lowcountry
88 manual lists 3 fusible links from starter solenoid on yellow wires - 18 gauge brown (N), link (W) 20 ga blue and 16 ga black link (M). It shows link (M) black 16 ga going to the 12 v supply for the ignition switch. It says the brown link supplies the EEC power relay and the blue link goes to fuse # 1 in the dash fuse panel (stop hazard lamps and cruise). Please cross check this with above info prior to using since I don't know the changes between 88 and 90, apparently there were continual changes thru thsi time period. If this looks right post back and I will try to answer any questions you have, if not suggest getting a Haynes manual for your own reference. Good luck.
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From: jax. florida
PROBLEM SOLVED.........
Thank you everyone for the help.....It was the fusible link going to the yellow wire near the battery......I found the the wire had a hole in the insulater and the wire blown in half.....spliced it back and it started right up and everything is working again....Thank you again
Thank you everyone for the help.....It was the fusible link going to the yellow wire near the battery......I found the the wire had a hole in the insulater and the wire blown in half.....spliced it back and it started right up and everything is working again....Thank you again
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From: Langhorne, PA
Good job!
The trick is to remove and replace that section of wire, known as the fusible link. I would stop at the parts store and get a new link and solder it in place. The link saved you once, so it is a good thing to have in the circuit.
PS/ No more electrical system maintenance with the battery connected.
The trick is to remove and replace that section of wire, known as the fusible link. I would stop at the parts store and get a new link and solder it in place. The link saved you once, so it is a good thing to have in the circuit.
PS/ No more electrical system maintenance with the battery connected.
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From: Central NY
Originally Posted by chmath
....I found the the wire had a hole in the insulater and the wire blown in half.....spliced it back and it started right up
Thanks for the update!
Popa Tim