Randomly Shutting off

I have a 1988 Bronco 302 EFI with an AOD Transmission. That has randomly been shutting off. When it shuts off all the idiot lights come on and will restart at the first turn of key every time. When it shuts off i have to turn the key back then restart vehicle, it will not restart if i do not turn key back. It will shut off at idle or at 70mph driving down a dirt road or a paved highway, on a hot day cold day wet or dry, when i accelorate or deccelorate,  just when it feels like it. I have replaced control module on distributor with a motorcraft module, ignition switch on top of steering colum, and a new pick up assy,  eec and fuel pump relay, computer ground, checked ground on the motor. i do think its a wiring problem but it is intermidate and i am at a lost of what to do wondering if anyone has any ideas. when it shuts off its just like i turned the key off

Yo,

Welcome!

Re your "ignition switch on top of steering column",

If you replaced the key lock cylinder and not the electrical switch at base of column, then try the IGN Switch Pin-Out Diagram & Continuity Testing (Logic Tables) in 80-91

http://api.viglink.com/api/click?format=go&jsonp=vglnk_146429307409712&key=6ed47b392b9edfe394b9e89b72717104&libId=iooq999o01000bgv000MAbkmxdu9o&loc=http%3A%2F%2Fwww.fullsizebronco.com%2Fforum%2F4194577-post4.html&v=1&out=http%3A%2F%2Fwww.supermotors.net%2Fregistry%2Fmedia%2F831772&ref=https%3A%2F%2Fwww.google.com%2F&title=Ford%20Bronco%20Forum%20-%20View%20Single%20Post%20-%20Bad%20ignition%20switch%3F&txt=http%3A%2F%2Fwww.supermotors.net%2Fregistry%2Fmedia%2F831772

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/?pid=74587&mode=threaded

Some basics;

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears including Reverse.

Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.

Then turn off engine, all accessories/lights (close driver's door) , etc.

Do KOEO test First

Post Code(s) here according to:

KOEO

&

KOER

Dom you think it shuts off when you run over a bump or expansion joint in the road?

If so, Ford does suggest a wiggle test..

Key On Engine Off Wiggle Test Procedure

1.Hook up a STAR Tester, VOM or Scan Tool.

2.Turn the ignition key to the ON position.

3.For STAR Tester or VOM, activate, deactivate and reactivate Self-Test to enter Continuous Monitor Diagnostic Test Mode (DTM). For Scan Tool, enter DTM, then enter wiggle DTM.

4.Tap, move, and wiggle the suspect sensor and/or harness. When a fault is detected, a Continuous Memory DTC will be stored in memory and indicated as follows:

•STAR Tester: Red LED lights and/or continuous tone.

•Malfunction Indicator Lamp (MIL): Lights

•VOM: Needle Sweep

•Transmission Control Indicator Lamp (TCIL)

•Message Center (Continental Only)

•Scan Tool: Continuous Tone

Engine Running Wiggle Test Procedure

Special Note:

•The Engine Running Wiggle Test may be activated any time the engine is running.

1.Hook up a STAR Tester, VOM or Scan Tool as shown.

2.Key off.

3.Start the engine.

4.For STAR Tester or VOM, activate Self-Test, deactivate and reactivate Self-Test to enter Engine Running Continuous Monitor DTM. DO NOT shut the engine off. For Scan Tool, enter DTM, then enter wiggle DTM.

5.Tap, move, and wiggle the suspect sensor and/or harness or drive the vehicle. When a fault is detected, a Continuous Memory DTC will be stored in memory and indicated as follows:

•STAR Tester: Red LED lights and/or continuous tone.

•Malfunction Indicator Lamp (MIL): Lights

•VOM: Needle Sweep

•Transmission Control Indicator Lamp (TCIL)

•Message Center (Continental Only)

•Scan Tool: Beeps

GL!

I have done the Wiggle test with the vehicle running including both fuel pumps and ignition switch. yesterday I also disconnected the computer and did notice very slight corrosion so i cleaned and still vehicle shut off. 

Yo,

Ok.

Did you do Key On Engine Off (KOEO) Self-Test?

yes only codes i got were EGR related codes. I did discover yesterday my computer was war to the touch after driving witch tells me my problem is most likey a poor ground

Yo, OK

Any aroma of "electrical smoke" in etc area inside driver kick panel?

Burnt PCM pic in a 94; "...the capacitors inside burned and leaked on the board. it happened to all of them, one was worse then the others..." see Mike's pic here; http://img.photobuck...0069/ECM002.jpg

Next is to check etc power relay and fuel pump relays...wiring to each, each connector for corrosion, etc.

Fuel Pump Relay Socket Corrosion Info; "...if you had corrosion in your relay socket, then you probably have it other places. one at a time unplug all relays and connectors on that fender and spray them down with contact cleaner. then after you let that do it's job for about 30min-1hr, go back and unplug each relay and connector again (one at a time) this time put them together with di-electric grease. you can buy a tube of it from any electrical/electronics supply or auto store. make sure you get everything plugged back in..."

EEC Relay Pin-Outs (Partial) in 88-89 & 90-91 Bronco 4.9; 88-90, 91 & 92-93 Bronco 5.0; 88-91 & 92-93 Bronco 5.8; Looking Into Harness Connectors in Ford Electronic Engine Control Overview, Chapter 12, of Ford Fuel Injection and Electronic Engine Control: How to Understand, Service and Modify, 1988-1993 Charles O. Probst via http://web.archive.org/web/20110704143230/http://www.yunost.ru/docs/Ford-injectors-book/Part12/Part12-4/Part12-4.pdf

EEC, Fuel Pump, etc. Relay Location in a 90; on driver's side fender apron

Source: by Seattle FSB



Or because Ford did some location changes in 80s

EEC Relay Location in an 86; "...On some 86's (like mine) you will find the EEC Relay in the cab to thr right of the gas pedal...sorta where your ash tray would be..."

Of course, we would have to test ignition, fuel and other things.

How was the ignition switch test?

Have to think about setting up a temporary 12 volt test light to show by when coil has primary battery voltage.. but...

Later.

Yo,

EEC Ground is G203

Wiring diagram at

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21071

G203 RH rear side of radiator support

location pic in an 89; "...Those wires eventually connect back to the EEC case (which is grounded) and the pins on the connector that need to be grounded...but then again every ground connects to each other on a Bronco..." by Will H.

http://web.archive.org/web/20151226014428im_/http://www.supermotors.net/getfile/110836/fullsize/img_0346.jpg

Sorry it took awhile to respond thanks for your help. no smell of electrical smoke. but i did discover the computer is my problem it is randomly shutting off the injectors, and the motor never losses fuel pressure before it dies. i have another computer on order, will let you know if it solves the problem. Also i know it is not my TPS because i unplugged it and it still shuts down.

Yo,

Ok. Thanks for getting back here.

fyi,

TPS Test, Operational Description & Parameters

by Ryan M. at

http://web.archive.org/web/20101201014211/http://fordfuelinjection.com/index.php?p=30

Let us know how it goes.

well i found the problem it was pick up coil. I over looked it 1 because I just replaced the whole distributor about 8 months ago, and 2 because it would immedietly fire back up and run after it shut off and as we know thats not like a pick up coil. thanks for all your help. glad I got it fixed was about to drive me crazy, never had a vehicle whoop my asz so bad.

Yo,

Great that you solved it and for getting back to us!