94 Ranger will not start - need help trouble shooting

1994Splash · 07-15-2011, 01:55 PM

I have a 1994 Ranger that will not start. The problem occurred after it was started and was running for just a minute and the engine just died and would not restart

With key on only the battery light comes on; the abs light is on momentarily. When cranking no other lights come on.
The fuel pump never runs. Fuel pump, Fuel pump relay, fuel pump fuse and the Inertial FP switch are all good. Using the EEC test plug and grounding pin 6 the fuel pump runs.

I am getting spark at the plugs – I don’t have a test light to verify that it is hot enough but it seems very strong.

I am lost as to trace the circuits further. Any help would be greatly appreciated.

07-15-2011, 01:58 PM

Does the check engine light come on for a few seconds when you first turn the key on? If not, check the EEC fuse in the PDB under the hood.

1994Splash · 07-15-2011, 02:13 PM

The check engine light does not come on. The 30 Amp EEC power fuse is good - all of the fuses in the PDB test ok.

I did notice that the Check Oil, Brake light and Seatbelts lights are on when cranking.

Thanks

07-15-2011, 02:22 PM

If the CEL isn't coming on (assuming the bulb isn't burnt out) then your computer isn't getting power and therefor the truck will not run. Is there power to the PDB? Is there power at the hot side of the EEC fuse?

1994Splash · 07-15-2011, 02:40 PM

The check engine light was working. I measure 12 volts at the fuse. I see that it feeds a yellow wire back into the wiring harness. I am not sure how to check at the computer....

with key on the EEC power relay is engaged (12 volts at pins 87 and 30). If there is fuse or fuse link after that I do not know how to find it..

07-15-2011, 02:57 PM

There should be two yellow wires. One wire goes to pin 1 on the PCM (EEC) and the other goes to the PCM relay.

The computer is located behind the passenger side kick panel. Check to see if you have power at pins 37 & 57 (the only solid red wires) with the key on.

I went through a similar situation a little over a year ago. http://www.explorerforum.com/forums/...d.php?t=255098
There is a wiring diagram in post #16

1994Splash · 07-15-2011, 03:50 PM

Thanks- I am still reading thru the thread but on my ranger the pcm is not behind the passenger kick panel. My Haynes manual indicates that it is located the upper edge of the firewall on the passenger side. It is not. I am not exactly sure what it should look like but I think that it may be low on the firewall on the drivers side. That is the only computer plug like device that I can find and I am not exactly sure how I am going to get to it to test it.

Does that make sense?

1994Splash · 07-15-2011, 06:46 PM

I tried to read any codes on the EEC self test. With key on - I got no voltage - no pulses, nothing. With Key Off it measured 12 volts.

I did check the 2 red leads and 1 yellow lead at the connector of the PCM. All three measured 12 volts.

The check engine light is not on when trying to start.

I do not know any other way to check to see if the PCM is bad before replacing it.

Is there any other circuit I can check, or am I at the point of replacing the PCM?

Does the PCM generally just die? or does it sort of fail in stages?

MrShorty · 07-15-2011, 09:57 PM

Quote:

Does the PCM generally just die? or does it sort of fail in stages?

Yes, sometimes it just up and dies, and sometimes it fails in stages.

Quote:

Is there any other circuit I can check, or am I at the point of replacing the PCM?

Don't forget to check the grounds (pins 20, 40, and 60, if memory serves. You could use a wiring diagram to verify). If it has good power and good grounds, and is not responding, then it could very well be a bad PCM. Especially where the PCM ground splices into the battery cable. Many report corrosion at that splice.

1994Splash · 07-15-2011, 11:13 PM

Quote:

Especially where the PCM ground splices into the battery cable. Many report corrosion at that splice.

Not sure what you mean. Are you referring to corrosion in the connector or somewhere in the wiring harness?

MrShorty · 07-16-2011, 09:54 AM

If memory serves, there isn't a connector in two of the ground wires between the PCM and the battery cable. The splices are inside the cable or at the battery post itself. It's been a few years, but it seems like one of my ground wires cracked, which exposed them to the air, which allowed the wire to corrode.

I don't mean to overly complicate the discussion -- the basic idea is simply to make certain the grounds are still intact before declaring the PCM itself at fault.

1994Splash · 07-16-2011, 11:54 AM

I just measured the grounds using and old Fluke 8010A uncalibrated for 10years.
At the connector;
P40 and P60- (B/W leads) 60.5mv
P20- (B/W/grn) 3.3mV

12.01 volts battery (key off) - 11.85 with key on.
Pin1 (yel) - 11.85 volts.

Are the grounds good enough? or is the impedance too high and I should be tracing wires and splices?

Thanks for your inputs, I am still concerned that there is something that I am missing.
I ran the battery down last night because I left the key on. The PCM relay runs rather warm.

MrShorty · 07-16-2011, 06:15 PM

When my ground wires had problems, I had several hundred mV voltage drop across the ground and, even at that, I don't recall it not starting. 3.3 mV seems fine. 60 mV might be a little high, but not excessively so. I might look at the wires a little more carefully to make sure there aren't any obvious faults. Maybe even rig a temporary ground to make sure. It's looking more like the PCM might be bad.

1994Splash · 07-16-2011, 07:10 PM

Thanks MrShorty,
I pulled the ECM and it smells as though it is fried.

I found something that indicated anything under 0.1V was acceptable while researching computers. It appears that the one in my truck is the most expensive of the bunch for 1994. Its part number F47F 12A650-ANB. It looks like the parts stores are ordering them on demand. I hope I can have one here by Tues. I hope that it is a drop in replacement- and it just works.

I have been pulling wires and looking into connectors and overall I am pretty satisfied with how things look. Corrosion does not seem to be too bad anywhere.

I do wonder if something else has failed and taken the computer with it.

1994Splash · 07-16-2011, 09:10 PM

Are there any differences between cardone reman ecms and BWD reman ecms? It would seem that I can get a BWD one for ~100$ vice ~225$ for the cardone one..

Kravist · 08-12-2011, 12:39 AM

Have you changed out the PCM? What was the result if so? Thanks! Your thread is helping me with my problem.

eureka77 · 10-07-2012, 03:10 PM

WTF was it???

Kravist · 10-08-2012, 03:45 AM

On my truck, it was the crankshaft position sensor. A simple and CHEAP fix.

eureka77 · 10-08-2012, 08:26 PM

So the crankshaft sensor kept the eec/or pcm from getting power? Appreciate it bud will check it out.
My prob. was it cut out while driving at 50mph, like it was running out of gas. Pulled to the side of the road and it cranked back up and died shortly after. Couldn't hear the fuel pump run so thought that was it. Replaced the fuel pump all fuses and relays in the PDB., new inertia switch and new eec/or pcm. Still doing the same thing. If I kept messing with the key off, on, off on, for a length of time I'll get a check engine light for awhile, hear the fuel pump all is normal, then just dies again. Was this your problem too?
Thank you for responding.

Kravist · 10-09-2012, 05:23 AM

When the crankshaft position sensor is bad, it is telling the PCM that the crankshaft is not in the correct place to start (and possibly run). I was getting fuel, as evidenced by a fuel pressure gauge that I put it at the fuel rail -- so I was able to eliminate a lot of things right there.

My problem was intermittent. Sometimes if the vehicle would sit for a while, or if I pushed it a few feet it would start. And if I did get it started, it would want to die if I didn't give it lots of gas.

I know that it is frustrating. Keep at it. You will figure it out.

07-15-2011, 02:40 PM	#5
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	The check engine light was working. I measure 12 volts at the fuse. I see that it feeds a yellow wire back into the wiring harness. I am not sure how to check at the computer.... with key on the EEC power relay is engaged (12 volts at pins 87 and 30). If there is fuse or fuse link after that I do not know how to find it.. Last edited by 1994Splash; 07-15-2011 at 02:53 PM.

07-16-2011, 09:54 AM	#11
MrShorty Wannabe Elite Explorer Spanish Fork, UT 92 XLT and '87 Bronco II Join Date: Dec 2001 Posts: 4,934 Vehicle Specs	If memory serves, there isn't a connector in two of the ground wires between the PCM and the battery cable. The splices are inside the cable or at the battery post itself. It's been a few years, but it seems like one of my ground wires cracked, which exposed them to the air, which allowed the wire to corrode. I don't mean to overly complicate the discussion -- the basic idea is simply to make certain the grounds are still intact before declaring the PCM itself at fault. __________________ Mr. Shorty 92 XLT 4x4 87 Bronco II XLT 4x4 '98 Chev K1500 Suburban SLT 4x4

07-16-2011, 06:15 PM	#13
MrShorty Wannabe Elite Explorer Spanish Fork, UT 92 XLT and '87 Bronco II Join Date: Dec 2001 Posts: 4,934 Vehicle Specs	When my ground wires had problems, I had several hundred mV voltage drop across the ground and, even at that, I don't recall it not starting. 3.3 mV seems fine. 60 mV might be a little high, but not excessively so. I might look at the wires a little more carefully to make sure there aren't any obvious faults. Maybe even rig a temporary ground to make sure. It's looking more like the PCM might be bad. __________________ Mr. Shorty 92 XLT 4x4 87 Bronco II XLT 4x4 '98 Chev K1500 Suburban SLT 4x4

07-16-2011, 09:10 PM	#15
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	Different Manufacturers of Computers Are there any differences between cardone reman ecms and BWD reman ecms? It would seem that I can get a BWD one for ~100$ vice ~225$ for the cardone one..

07-15-2011, 01:55 PM	#1
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	94 Ranger will not start - need help trouble shooting I have a 1994 Ranger that will not start. The problem occurred after it was started and was running for just a minute and the engine just died and would not restart With key on only the battery light comes on; the abs light is on momentarily. When cranking no other lights come on. The fuel pump never runs. Fuel pump, Fuel pump relay, fuel pump fuse and the Inertial FP switch are all good. Using the EEC test plug and grounding pin 6 the fuel pump runs. I am getting spark at the plugs – I don’t have a test light to verify that it is hot enough but it seems very strong. I am lost as to trace the circuits further. Any help would be greatly appreciated.

07-15-2011, 01:58 PM	#2
geoph1986 Unregistered Posts: n/a Vehicle Specs	Does the check engine light come on for a few seconds when you first turn the key on? If not, check the EEC fuse in the PDB under the hood.

07-15-2011, 02:13 PM	#3
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	The check engine light does not come on. The 30 Amp EEC power fuse is good - all of the fuses in the PDB test ok. I did notice that the Check Oil, Brake light and Seatbelts lights are on when cranking. Thanks

07-15-2011, 02:22 PM	#4
geoph1986 Unregistered Posts: n/a Vehicle Specs	If the CEL isn't coming on (assuming the bulb isn't burnt out) then your computer isn't getting power and therefor the truck will not run. Is there power to the PDB? Is there power at the hot side of the EEC fuse?

07-15-2011, 02:57 PM	#6
geoph1986 Unregistered Posts: n/a Vehicle Specs	There should be two yellow wires. One wire goes to pin 1 on the PCM (EEC) and the other goes to the PCM relay. The computer is located behind the passenger side kick panel. Check to see if you have power at pins 37 & 57 (the only solid red wires) with the key on. I went through a similar situation a little over a year ago. http://www.explorerforum.com/forums/...d.php?t=255098 There is a wiring diagram in post #16

07-15-2011, 03:50 PM	#7
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	Thanks- I am still reading thru the thread but on my ranger the pcm is not behind the passenger kick panel. My Haynes manual indicates that it is located the upper edge of the firewall on the passenger side. It is not. I am not exactly sure what it should look like but I think that it may be low on the firewall on the drivers side. That is the only computer plug like device that I can find and I am not exactly sure how I am going to get to it to test it. Does that make sense?

07-15-2011, 06:46 PM	#8
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	I tried to read any codes on the EEC self test. With key on - I got no voltage - no pulses, nothing. With Key Off it measured 12 volts. I did check the 2 red leads and 1 yellow lead at the connector of the PCM. All three measured 12 volts. The check engine light is not on when trying to start. I do not know any other way to check to see if the PCM is bad before replacing it. Is there any other circuit I can check, or am I at the point of replacing the PCM? Does the PCM generally just die? or does it sort of fail in stages?

07-16-2011, 11:54 AM	#12
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	I just measured the grounds using and old Fluke 8010A uncalibrated for 10years. At the connector; P40 and P60- (B/W leads) 60.5mv P20- (B/W/grn) 3.3mV 12.01 volts battery (key off) - 11.85 with key on. Pin1 (yel) - 11.85 volts. Are the grounds good enough? or is the impedance too high and I should be tracing wires and splices? Thanks for your inputs, I am still concerned that there is something that I am missing. I ran the battery down last night because I left the key on. The PCM relay runs rather warm.

07-16-2011, 07:10 PM	#14
1994Splash Wannabe Elite Explorer madison,al 94 Splash Join Date: Jun 2010 Posts: 15 Vehicle Specs (Original Poster)	Thanks MrShorty, I pulled the ECM and it smells as though it is fried. I found something that indicated anything under 0.1V was acceptable while researching computers. It appears that the one in my truck is the most expensive of the bunch for 1994. Its part number F47F 12A650-ANB. It looks like the parts stores are ordering them on demand. I hope I can have one here by Tues. I hope that it is a drop in replacement- and it just works. I have been pulling wires and looking into connectors and overall I am pretty satisfied with how things look. Corrosion does not seem to be too bad anywhere. I do wonder if something else has failed and taken the computer with it.

08-12-2011, 12:39 AM	#16
Kravist Wannabe Elite Explorer 97 ExplorerSport 4.0 SOHC Join Date: Aug 2011 Posts: 7 Vehicle Specs	Any Updates? Have you changed out the PCM? What was the result if so? Thanks! Your thread is helping me with my problem.

10-07-2012, 03:10 PM	#17
eureka77 Wannabe Elite Explorer 94 ranger ext. cab Join Date: Oct 2012 Posts: 17 Vehicle Specs	WTF was it???

10-08-2012, 03:45 AM	#18
Kravist Wannabe Elite Explorer 97 ExplorerSport 4.0 SOHC Join Date: Aug 2011 Posts: 7 Vehicle Specs	On my truck, it was the crankshaft position sensor. A simple and CHEAP fix.

10-08-2012, 08:26 PM	#19
eureka77 Wannabe Elite Explorer 94 ranger ext. cab Join Date: Oct 2012 Posts: 17 Vehicle Specs	So the crankshaft sensor kept the eec/or pcm from getting power? Appreciate it bud will check it out. My prob. was it cut out while driving at 50mph, like it was running out of gas. Pulled to the side of the road and it cranked back up and died shortly after. Couldn't hear the fuel pump run so thought that was it. Replaced the fuel pump all fuses and relays in the PDB., new inertia switch and new eec/or pcm. Still doing the same thing. If I kept messing with the key off, on, off on, for a length of time I'll get a check engine light for awhile, hear the fuel pump all is normal, then just dies again. Was this your problem too? Thank you for responding.

10-09-2012, 05:23 AM	#20
Kravist Wannabe Elite Explorer 97 ExplorerSport 4.0 SOHC Join Date: Aug 2011 Posts: 7 Vehicle Specs	When the crankshaft position sensor is bad, it is telling the PCM that the crankshaft is not in the correct place to start (and possibly run). I was getting fuel, as evidenced by a fuel pressure gauge that I put it at the fuel rail -- so I was able to eliminate a lot of things right there. My problem was intermittent. Sometimes if the vehicle would sit for a while, or if I pushed it a few feet it would start. And if I did get it started, it would want to die if I didn't give it lots of gas. I know that it is frustrating. Keep at it. You will figure it out.