Engine doesnt turn off

[cymmij]

I have an 88 GT and the other day I parked the car turned off the key switch radio and other accessories turned off but not the engine had to pull the fuel pump relay to get it to shut off. The ECM also stays powered up also till you remove the ground So I figured key switch good ignition switch not soo much so I replaced the ignition switch but it still does the same thing any ideas??

 

[jrichker]

Did you replace the key part of the ignition swich or the electrical part? Replacing the key part won't fix any electrical problems.

If you replaced the electrial part of the ignition switch, then replace the ECC relay: it is probably sticking.

Diagram courtesy of Tmoss & Stang&2birds

The ECC relay is mounted on top of the computer: you have to remove the computer to replace it. The computer is under the passenger side kick panel. The computer mount is two 10/32 screws that secure a plastic strap diagonally across the computer case. Removing the passenger side dash speaker may help some. I recommend that you enlist someone with small hands to help you with the relay since the working space is very small.


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

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for94-95 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/94-95_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


If you have an aftermarket car alarm or stereo, you may be in for a lot of time searching for possible crosswired circuits.

 

[cymmij]

I thought that relay was on the pass. side fender??

 

[HISSIN50]

It's above the EEC in the passenger kick panel.

The relay in the engine compartment along the fender is the WOT relay.

 

[cymmij]

Should that be energized only at WOT because that and the EEC relay are staying energized until I remove the ground at the battery.

 

[HISSIN50]

The WOT relay is only closed at WOT. It shuts off the AC compressor clutch coil at WOT to free up HP. Otherwise, during (non-WOT) power for the clutch goes through the N.C. and common terminals (the relay is at rest).

Check the WOT relay for shorted wires near the socket. Heat vulcanizes the insulation and the wires can short.

If the EEC relay is really staying hot at all times, are other accessory ignition circuits (like in the fusebox) staying hot as well? If so, check that ignition switch (electrical connector and wiring) again.

Good luck.

 

[cymmij]

No the radio and fan and stuff all turn off with the key switch I am confused.

 

[jrichker]

No the radio and fan and stuff all turn off with the key switch I am confused.

Go back to my previous post and don't just look at it, study the diagram.

Have you added anything electrical to the car recently? Stereo, alarm system, Tach, gauges? If so, the additional wiring for them could be the source of the problem.


Did you replace the electrical part of the switch where all the wires plug into or just the key?

Diagram courtesy of Tmoss & Stang&2birds

 

[cymmij]

Im sorry jrichker I did'nt answer your question I replaced the actual electrical switch not the key switch. Now after finding out the actual location not the assumed (i know i know) location for the EEC relay and studying the excellent diagram by tmoss I see that I have some melted wires and stuff at the WOT relay so I am thinkin since the EEC and WOT relays appear to be related that may be the source of my problem so we shall see I know have some melted wires and stuff to fix.

 

[liljoe07]

I cant see it being the ECM relay. For one, the igntion switch cuts off power to the coil and TFI if its working correctly. I could be wrong though.

 

[jrichker]

I cant see it being the ECM relay. For one, the igntion switch cuts off power to the coil and TFI if its working correctly. I could be wrong though.

You are correct, I missed that one. The only things that could energize the ignition coil and the ECM relay are a failed ignition switch or something crosswired power back to the red/green wire on the ignition coil or TFI.

 

[5OhToGo]

I have a slightly similar problem. I have 91 with a stock 5.0. I started the car about a month ago like normal but when I let off the key it revved above idle and the starter was still trying to turn as if I was holding the key on start. When I turn the key off the engine kept running. I had to stall it. A few minutes later it started fine. It happened a few more times. Once after I stalled it and took the keys out I pressed the clutch back in and it started again. Several times later it started the same way and after I stalled the car the starter cut on while I was out of the car holding the keys in my hand. The car was in neutral and it sounded like it was grinding so I disconnected the battery. I replaced the fender solenoid and the starter and its solenoid. The problem still remains. The ignition cylinder is still intact and I replaced the rectangular electrical part of the ignition. The cylinder still seems to work fine. Any ideas?