Need help ASAP before i burn this car...

[RCwhat]

Please bear with me......So I have a 1990 LX 5.0 with the ssp package...car ran great and was getting ready to drop in a new motor and supercharger in the coming days. Well I figured that I'd take her for one last Joy ride before tearing her apart. So i get in the car turn the key....and nothing...won't even attempt to turn over, no fuel pump priming, no turn signals....nothing. The only things that work are the headlights, dome light and warning buzzer for door being open. I kept trying to start it, moving the key back and forth and pushing the clutch in and out then all of a sudden it started but then died and no luck since (This happened about a week ago). Now fast forward to this week, i've replaced the ignition switch on the column (the one with two security torx bits, PITA!), the actual key ignition switch, and the eec relay....and still nothing. I also tried bypassing the clutch safety switch by jumpering both connectors. I checked for Vref (5v) at the tps sensor and got nothing...so i think its safe to say that the computer is never turning on....the last thing on my list is the computer but no junk yards around me have any and i'm kind of all set with paying a few hundred for something that may have nothing to do with it. Someone told me about some fuseable links?? but i can't find any under the dash. The car will turn over if i jump the solenoid but will not fire, so its definitely something computer related I THINK??? Any help is appreciated more than words can express, I'm just so freakin pissed that this is happening a week before I planned on swapping in a whole new drivetrain.....grrrrr thanks guys.:SNSign:

 

[jrichker]

The electrical part of the ignition switch is defective. They overheat and sometimes catch fire. That burns up the steering column and sometimes the car interior. The auto parts stores sell the switches for $13-$15.

If you have replaced the electrcal part of the ignition switch, check the wiring connector for the ignition switch. The plastic shell will often overheat and allow the connector pins to fall out or lose contact.

 

[RCwhat]

anyone have the pinout of the ignition switch so i can check if its getting voltage and also if its sending power to the eec relay????....

 

[jrichker]

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Engine Information Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[RCwhat]

thanks man.....much appreciated
gonna go break out the fluke dmm now...

 

[RCwhat]

also does anyone know where the fuseable link from the ignition switch to the eec relay is located???? thanks

 

[RCwhat]

ok, i think the autozone ignition switch might be junk. The two yellow wires (which should be supply voltage) both show ~12.6v with the key off but as soon as i turn the key to run they both drop to nothing 0v. The red/green wire that should supply voltage to the eec relay isn't showing any voltage no matter the key position. even if the fuseable link was bad i should still get voltage before it. Am I correct in assuming now that the autozone switch is junk???? with the stock switch it would sometimes start if i kept fiddling with the key enough but never anything anymore after i put the new switch in????

 

[RCwhat]

anyone??? before i go spend another $25 on a ford ignition switch.....

 

[seijirou]

anyone??? before i go spend another $25 on a ford ignition switch.....

Your fuseable link is on your starter relay post, battery side. If you've got 12v to the ignition block though, it's fine.

Do me a favor. Get yourself a ziptie, and ziptie that ignition block with all the wires coming out of it, up tight to the ignition column. Sometimes you need to daisy-chain zipties together to get one long enough. Get that thing ziptied tight up to the column and then re-test your wires and post up your results.

 

[jrichker]

ok, i think the autozone ignition switch might be junk. The two yellow wires (which should be supply voltage) both show ~12.6v with the key off but as soon as i turn the key to run they both drop to nothing 0v. The red/green wire that should supply voltage to the eec relay isn't showing any voltage no matter the key position. even if the fuseable link was bad i should still get voltage before it. Am I correct in assuming now that the autozone switch is junk???? with the stock switch it would sometimes start if i kept fiddling with the key enough but never anything anymore after i put the new switch in????

The symptoms you are having sound like a fuse link that has some high resistance connections or a bad connection at the fuse panel. Check out things that use fuse #1, like stop lights and hazard lights. If they work good, then the fuse link is good. That leaves a bad connection somewhere in the fuse panel area as being a possible problem.

The little rectangles with the squiggly line in them on the switch drawing are supposed to be inline connections. They can easily develop high resistance connections from corrosion and age. The same problem is also common in the yellow wire connections at the ignition switch.

 

[RCwhat]

update

Just wanted to update this after finding the source of the problem. (because you don't know how many "not starting" threads i searched for and read that nobody updated once they fixed their car. So i had tons of people with similar symptoms but nobody ever wanted to post what finally fixed it.) Anyway after taking the advice of people here and realizing that it is a SSP car that used to have multiple electronic devices i started hunting through the wiring in the engine bay. Well i ended up finding a huge batch of wires all taped together that looked like hell. So i started taking all the elec. tape off and low and behold there were like 8 wires all twisted together all green with corrosion. So i cut them all, rewired them into a distribution block i had laying around from an old car audio project, jumped in the car, turned the key and finally heard the sweet humming of the fuel pump turned it to start and she fired right up. Now i can start ripping the drivetrain out with peace of mind that it should start back up after the swap. Thanks StangNet esp. jrichker for all your help. :SNSign:

 

[old_blue]

thanks for posting the update, i dont like when people find the problem then dont post what it was.

 

[jrichker]

Sometimes you can be the victim of other people's good(???) intentions when it comes to electrical stuff...

 

[seijirou]

Sometimes you can be the victim of other people's good(???) intentions when it comes to electrical stuff...

Amen to that.

 

[RCwhat]

just my luck, after finally getting the whole drivetrain back together....the damn thing won't start again. going out right now to start troubleshooting again...she cranks and cranks but no fuel pump priming and no voltage at the eec relay.....grrrrr. any ideas?

 

[seijirou]

just my luck, after finally getting the whole drivetrain back together....the damn thing won't start again. going out right now to start troubleshooting again...she cranks and cranks but no fuel pump priming and no voltage at the eec relay.....grrrrr. any ideas?

Well if you don't have any constant power *IN* to the relay it shouldn't be too hard to find. The only thing between that and the battery could be a fuse, a fusable link, and perhaps a connector or two.

If all of that appears to be good I would disconnect the + cable from the battery, set your multimeter to continutity and start testing down the wire from the relay and work your way back towards the battery until you find where the continuity break is.

 

[RCwhat]

ok, i fixed the eec relay power issue. My dumbass had disconnected some off the fuseable links while rewiring things when i put the new motor in and forgot to reconnect one. Now the eec relay and fuel pump relay under the seat both have power but the fuel pump still isn't turning on. (not priming when turning the key on and no pressure on my FP gauge.) Its a brand new walbro 255 that i put in last week, never used or powered once. It sucks too because i just hand poured like 8 gallons of gas in it a few days ago. Now it looks like I gotta drop the damn tank again.

 

[2000xp8]

Glad you fixed it.
For the record, never buy electronic parts from a chain store.
If a ford part is available, buy it. Even if it's 2-3 times more money.

 

[seijirou]

ok, i fixed the eec relay power issue. My dumbass had disconnected some off the fuseable links while rewiring things when i put the new motor in and forgot to reconnect one. Now the eec relay and fuel pump relay under the seat both have power but the fuel pump still isn't turning on. (not priming when turning the key on and no pressure on my FP gauge.) Its a brand new walbro 255 that i put in last week, never used or powered once. It sucks too because i just hand poured like 8 gallons of gas in it a few days ago. Now it looks like I gotta drop the damn tank again.

Double check all the terminals on the fuel pump relay. I can't remember the numbers on relays any more to save my life. But if it's working correctly you should see +12 on 3 of the 4 terminals. The 4th terminal is computer-provided ground. So make sure you're getting ground to it as well. If not, the computer itself may not be coming on.

After that, check the inertia switch in the back. You can safely unplug it and jump the wires to test.

Might as well check that stuff before dropping the tank, if you havn't checked them already.

 

[RCwhat]

yeah i have 12v at one wire on the fuel pump relay with the key off. When i turn the key to the run position I get 12v at 3 of the wires. I swore i was getting like 6v at the last wire though, gonna have to recheck. I did unhook the ecu to install a tweecer too so hopefully thats not fried...although the fuel pump relay is getting switched power when i turn the key and according to schematics that signal comes from the ecu so am I correct in thinking that the ecu should still be Ok since the fuel pump relay is getting power when i turn the key?? The inertia switch is fine, was one of the first things i checked.