Ford Ranger PCM problems?
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6th Gear
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Ford Ranger PCM problems?
2011 Ranger 4.0 electronics problem. 54,000 mi. Running good. Parked for a week to replace rack and pinion and general clean up. Took for test drive. Ran good for a few minutes than engine cut out until idle was reached and resumed the cycle. Got home, pluged in the scanner, Aa good one. No codes. went to live stream, graphic. Everything normal except PCM vpwr. At start vpwr was 13.5 volts. normal . But after a couple of minutes it climbed to 24-26 volts????. At that point it would run 30 seconds- 1 min than cut out until idle and the cycle would continue to repeat.Checked crank position output, normal, CPM, normal, alternator, normal, fuel pressure normal, eng temp normal, MAF normal. Checked plugs and harness, normal. I am a mechanic by trade, have worked with Ford EEC. Where is the 24-26 volts coming from. Volt meter connected during tests.Changed PCM relay with another.Have not got out my wire ***** tools to check voltage at the PCM yet but if the supplied voltage is 13.5, why. Am worried its a PCM problem but where does the 24- 26 volts come from???.
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From: SW Va
Welcome to FTE.
Sounds like a alternator regulator problem. I'd not run the engine as that much over-voltage could fry a number of things. Maybe consider removing the alternator & having it bench tested, most auto parts stores can do this at no cost. Some beginning thoughts for consideration, let us know what you find.
Sounds like a alternator regulator problem. I'd not run the engine as that much over-voltage could fry a number of things. Maybe consider removing the alternator & having it bench tested, most auto parts stores can do this at no cost. Some beginning thoughts for consideration, let us know what you find.
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From: SW Va
Woooops, I just re-read your initial post & see you said you were using a volt meter during all the tests to monitor alternator output. SO, like you, I wonder where the voltage doubling is coming from if the alternator output is remaining within limits???
In case its a scan-tool or program problem, do you have a ELM scan-tool & can load & run FORScan on it to have a look at things to see if its seeing the same things.
I'm also thinking if the high voltage reading the scan-tool sees is a pulse thats short lived & the volt meter is analog, it might not be sensitive / fast acting enough to see a quick occurring voltage surge / spike on its analog meter??? More thoughts for consideration, let us know what you find.
In case its a scan-tool or program problem, do you have a ELM scan-tool & can load & run FORScan on it to have a look at things to see if its seeing the same things.
I'm also thinking if the high voltage reading the scan-tool sees is a pulse thats short lived & the volt meter is analog, it might not be sensitive / fast acting enough to see a quick occurring voltage surge / spike on its analog meter??? More thoughts for consideration, let us know what you find.
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6th Gear
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Got out my wite poking and pluf insertion stuff and measured at the PCN plug. Read battery voltave. A PCM repair busness in town said the internal voltage regulator inside of the PCM can be at fault over a failing capacitor. They are going to test the PCM for $50. So off it goes today. Will report on what is found. Thanks for the input
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From: SW Va
That sounds plausible, a pesky leaky cap can muck things up for sure, will be interesting to hear whats found.
FORScan has a Oscilloscope scan mode, or if your scan-tool has that feature & it can see fast acting spikes, have it take a look at the alternator output.
Haven't used my ELM running FORScan in the "O" scope mode in about 10 years, so cant remember how sensitive it was in that mode for displaying spikes, anyway have a look at the alternator output on something that can see fast acting spikes, before taking it to the shop, might save $50!!! lol
FORScan has a Oscilloscope scan mode, or if your scan-tool has that feature & it can see fast acting spikes, have it take a look at the alternator output.
Haven't used my ELM running FORScan in the "O" scope mode in about 10 years, so cant remember how sensitive it was in that mode for displaying spikes, anyway have a look at the alternator output on something that can see fast acting spikes, before taking it to the shop, might save $50!!! lol
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6th Gear
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My scanner can read all available graphics. The PCM graph will start at battery volts for several minutes showing all the little variations than jump to 24 vplts, than a little while, cut off until idle than start the cycle again. At the engine stumble, the grounds disappears from the PCM control of the injectors and ignition until idle is reached and the cycle resumes
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From: SW Va
Now I'm talking about a Oscilloscope Line drawing display, not a changing digital number display. The line drawing steady state voltage level & any spikes that occur above, or below the steady state voltage being monitored during the sweep time, stay on the line drawing display until it reaches the end of its sweep. So if for instance the alternator output voltage regulator is acting out under load & looses control, maybe turning off, it would show a - / negative spike below the steady state line drawing voltage when its acting out, or it'll show a positive spike above the steady state line drawing if display voltage goes + / up, on the display.
The reason I'm thinking its a alternator regulator problem is because the computer is regulating the alternator voltage Down to its components, to something like 5 volts. Don't think the computer has any voltage doubling circuits doubling the alternator output to 26 to 28 volts.
The reason I'm thinking its a alternator regulator problem is because the computer is regulating the alternator voltage Down to its components, to something like 5 volts. Don't think the computer has any voltage doubling circuits doubling the alternator output to 26 to 28 volts.
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6th Gear
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My scanner displays in scope fashion. I can even store it or print it out. Talking to the guys that repaired the scanner last year for EVAP problems sugested removing the purge and vent solenoid plugs.EUREAKA. Suggested that I really examine the harness and grounds. If all is well, time to check out the PCM. Thanks for the helpful comments. I am usually not stumped with Ford EEC but this one drove me crazy . ..
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