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More trouble with 94 Ranger

Having another problem with my Ranger. It died on me the other day and towed it back home. It was acting like it wasn’t getting any fuel. I did a check engine light code test which told me the Powertrain Control Module PCM was out. I ordered one from rock auto and after it would still not start, got the same code. So I ordered a second one but payed a little more for it. Just put it in and nothing. Same code came up. These parts travel via Fed Ex. I wonder if these parts run over magnets or somthing that knocks them out? Does any one have experience with PCMs? I always disconnect the battery when I work on the truck so it is not that. The package did arrive with very little padding which is not like rock auto. Thanks for any input. Michael

Post the actual DTC.

Don’t interpret the meaning of the code.


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The trouble codes (DTC) only suggest a possible troubleshooting starting point, they do NOT tell you what to replace.

I don’t know what a DTC is.

Check engine light code = DTC which means Diagnostic Trouble Code

I get 33 and then 513.

The DTC 33 indicates a problem with the EGR circuit.

There is no DTC 513.

Count the flashes again.


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513 (O) Replace processor (PCM) (internal failure)

In Chilton; code 513 / internal voltage failure in PMC
A friend mentioned the voltage regulator might be bad. I didn’t mention that I wasn’t getting a spark at the plugs?

First off, Keep the original PCM if you still have it, don’t turn it in for a core charge. There’s a good chance the PCM is not the problem. First make sure the battery and alternator are working. Since the engine won’t start, you may have to remove the alternator and take it to a shop who has a fixture to test it. They can test the battery too at the same time. If both test out ok … hmmm … next I guess is to visually inspect the connectors that plug into the PCM. See any cranks, anything look burned, corroded? Look at the original PCM too, under a magnifying glass. Look for cracked traces on the surface of the pcb, parts that looked discolored, or coated with a white film. Still haven’t figured it out … hmm …

So you aren’t getting a spark at the plugs? Verify that remains the case w/the original PCM. If so, you’ll have to figure out why. Does the engine crank ok, but not start? And no spark produced during cranking? If so, when it cranks there’s a sensor somewhere (probably in the distributor) that tells the computer the engine is turning. So first thing to do is test if that sensor is working. There is usually an output from the PCM for the rpm signal. Find someone who knows how to use an o’scope and see if that signal is being produced during cranking. If you got no rpm signal, there’s probably something shorting out the precision voltage regulated 5 volt output from the pcm. Try disconnecting everything possible but that should still allow the engine to start. Like the map/maf sensor, engine coolant temp sensor, throttle position sensor, all of those probably connect to the pcm’s precision 5 volt output. Best if you can find a wiring schematic and find everything that connected to that output and disconnect it, then see if it measures 5 volts or not.

If you’ve never debugged an electronic part at this level, you’re probably going to have to get some help with this. An auto electric shop, etc. Or just some diy’er than has owned a early 90’s ranger. Best of luck.

Have you checked fuses?

Voltage regulator in the PMC not the voltage regulator for the alternator. Just clarifying but I don’t know anything about it.

Check your inertia switch\relay. Every Ranger that I’ve ever owned (5) has actuated and left me stranded for a few minutes. I either bypassed the switch or reset it. It’s beneath the glovebox…right behind the top of the carpet. It shuts off power to the fuel pump.

Thanks. Lot of info.

I have checked for continuity in the inline fuse and regulator. Found a bad diode in the fuse box. Replaced that but still nothing.

Well I had the ignition coils checked and they were both bad. Put new ones in but it still will not run.

The diagnostic chart in my diagnostic help service that we pay a monthly fee for is from Ford. The chart sez “513 key on engine off=replace ECM”. So obviously the ECM is bad and needs replaced. If you still have the old unit you may be able to find a used one at I say the old unit so you can get the correct part number as there’s about ten different ones for each of the three engines offered.

With a bad diode in the fuse box, bad coils, and a code indicating a faulty ECM, I’m wondering if you got an alternator problem of some kind that is outputting higher than normal voltage spikes. Or just higher than normal voltages. Do you notice your battery is going dry and the cells needing refilling more than usual? To test the alternator’s output you’d need to be able to start the truck, which you can’t. But you might be able to take the alternator to a shop who can test it off the car for voltage spikes or over-voltage.

After the new coils, are you now getting a spark at least? Or still no spark at the spark plugs?

No spark. I have tried two different EMCs bur still no go. I need to test the ignition control module and the crankshaft position sensor next bur to do that I have to buy a wire piercing probe for my multi meter. Thanks for the input.

Thank you everyone. The damn truck still will not run but I can’t spend any more time on it, It is going into storage for the summer and I will have to deal with it next fall. Thankx again fr all the good input. Michael