Engine won't shut off

[Bigblock79]

I have a 91 ranger Stx 4wd manual trans 4.0 won't shut off. Put new solenoid new headlight switch new lock cylinder and starter switch. Truck still won't shut off with key. Turn key off all cab power turns off but motor still idles.

 

[RonD]

EEC Relay is stuck closed, most likely.

In a '91 Ranger there are 3 relays under the power box in the engine compartment.
Unbolt the Power Box and lift it up, you will see 3 relays
Green base is Fuel Pump relay
Brown base is EEC relay
Black base is WOT(wide open throttle) relay.

EEC relay, when closed, powers the EEC(computer,PCM), the fuel injectors, and the spark system, so basically the engine
This power comes from fuse #8(30amp) in the power box I think, pull that fuse and engine will shut off.

EEC relay closes when key is turned on, then opens when key is turned off.
So either the relay is stuck closed or there is a short in the wiring giving it 12volts all the time, either way getting to it for testing would be the first step.

I believe all 3 relays are the same part number, so can be swapped for testing.

Google: 1991 ranger EEC Relay location

There are some pictures of where the relays are

 

[Bigblock79]

I have found the relays but the bases have find in different locations on the side thank you though I will try that

 

[Bigblock79]

Swapped out relays no change

 

[adsm08]

Did you really replace the headlight switch because the engine won't shut off?

Does it die if you pull the relay while it's running?

 

[Bigblock79]

Yes I did because I have heard of 3 trucks with that solution I have replaced every thing I can think of and yes it dies