Troubleshooting error codes

[slycer2002]

I have to apologize now, this is a little long winded. I have a 92 Ranger 3.0 2wd automatic, and today while I was driving it the check engine light came on. I noticed that the temp gauge was slowly climbing as well, though this may have nothing to do with the issue. It was hot outside.

Anyway, while I was driving the engine cut out completely. I dropped it into neutral and was able to start my truck right back up. A couple miles later, the check engine light came back on. This time I was right by an Autozone and pulled in there to have them check the codes for me. Come to find out the dumb*sses there don't HAVE a code reader for a 92 Ranger, so I had to hope I could make it home to get mine. This time, my truck didn't want to start. It finally did, and I made it home. Halfway there, the check engine light came back on but the truck didn't die.

When I pulled the codes, I got a KOEO code of 542, Fuel Pump Secondary Circuit Fault. The CM code I got was 512, KAM failure. The funny thing is, when I checked the memory of my code reader, it is also showing a code of 511, ROM failure, but it doesn't show whether this is KOEO or CM. Either way, I'm stuck and really don't know what to check first. When I turn the key on but don't start it, I hear the fuel pump whir and hear the relay under the hood click. Any ideas? Thanks in advance.

 

[slycer2002]

Update from Earlier...

Okay, here's an update. Tonight when the sun had gone down and things had really cooled off (82F vs 100F) I drove to Wal-Mart. The check engine light stayed off and I had no problems. I still hooked the code reader up when I got to Wallyworld and it still pulled a 542 in the KOEO test. For the CM codes, however, the 511 and 512 were gone. This time, it's pulling a 542 from CM as well. I'm starting to think that this is a wiring issue, possibly a bad or intermittant ground issue. Anybody else have any suggestions? Thanks again in advance.

 

[locovaca]

Looking at a wiring diagram I'm going to guess the fuel pump relay (or wiring involved with it) may be going out. There are two wires going to the EEC from the relay, the ground to energize the relay and one on the output side to monitor that the relay is working. If I had to guess the "secondary" is the output monitoring side. So the EEC is energizing the relay but not seeing the expected voltage on the output side and is throwing a fit.

I'd check the wiring, connectors, and grounds to make sure they were clean and in working order. I'd also swap a relay from a known working one and see if that helps.

 

[slycer2002]

Well, here's an update. I did an oil change and replaced the fuel filter on my truck and things got better so I figured maybe all I had was a plugged fuel filter. My old fuel filter rattled from the inside when I pulled it out so I figured that was it. I was wrong. My truck ran well for a couple of days and then started trying to die out again during normal operation. It got to the point where it was pretty much undrivable. I broke down and took it to the shop. Turns out my ECM is almost completely rotted. When they pulled it out and unhooked it, some of the pins actually FELL OUT. How does an ECM rot out? The only thing I can think of is I had my heater core replaced a few years ago and maybe the old one leaked before I had it replaced. It's not THAT far away. But anyway, I need a new ECM. Anybody have any suggestions? And before you tell me to go to a salvage yard, bear in mind the ones around me in Central IL suck and they don't have any Rangers. Thanks in advance!

 

[locovaca]

Well, here's an update. I did an oil change and replaced the fuel filter on my truck and things got better so I figured maybe all I had was a plugged fuel filter. My old fuel filter rattled from the inside when I pulled it out so I figured that was it. I was wrong. My truck ran well for a couple of days and then started trying to die out again during normal operation. It got to the point where it was pretty much undrivable. I broke down and took it to the shop. Turns out my ECM is almost completely rotted. When they pulled it out and unhooked it, some of the pins actually FELL OUT. How does an ECM rot out? The only thing I can think of is I had my heater core replaced a few years ago and maybe the old one leaked before I had it replaced. It's not THAT far away. But anyway, I need a new ECM. Anybody have any suggestions? And before you tell me to go to a salvage yard, bear in mind the ones around me in Central IL suck and they don't have any Rangers. Thanks in advance!

Visit car-part.com. Lots of them in the area. Decatur Auto Parts supposedly has two.

 

[slycer2002]

Visit car-part.com. Lots of them in the area. Decatur Auto Parts supposedly has two.

Thanks for the info! I wasn't aware of that website. Unfortunately, the two that are located at Decatur Auto Parts are for trucks with manual transmissions. Mine is an automatic. The closest I've found is Southwest Auto Salvage in Lockport, IL. I may have to give them a call anyway and get some more info. They didn't list the condition or the price on the website. But thanks again!