Electrical Issue
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Cross-Country
Joined: Oct 2012
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Electrical Issue
I am working on my fathers 1997 Ford F150 XL Extended cab with 4.2 V6. I thought it was a bad fuel pump and changed it out with no luck still. What I have is this: Truck cranks but does not run, fuel pump does not power up, checked all the fuses in the main control box under the hood. checked all the relays for proper operation. PCM relay clicks and does work, fuel pump relay does not click. I have read to take the fuel injector 1 plug off and check for voltage, im not sure if the one I pulled off is fuel injector 1, driver side at front, but it does not have voltage going to it. PCM was replaced around 2005 by the dealership which said the windshield was leaking and got water on it, (also replaced windshield cause of the statement). Currently lost and have no idea where to go next. I will be available to work on it with any help at all. Thanks for every ones help. 
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Cross-Country
Joined: Oct 2012
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Yes I kept that in mind, and asked dad to turn then key to run position while I rocked the relay back and forth to see if it clicked like the PCM relay, still nothing and it does not energize. Is there any way to check to see if the PCM is bad? Check engine light is not on when the key is in the run position.
Fleet Owner
Joined: Mar 2012
Posts: 26,065
Likes: 4,145
From: Near Cal. Avenue
Make sure your fuel pump power cutout is energized. Navigate to the top of page and type in enertia switch in search. Try different types of enertia questions. Check Ground for the circuit at the body/frame.
Fleet Owner
Joined: Mar 2012
Posts: 26,065
Likes: 4,145
From: Near Cal. Avenue
The easiest way to answer is to navigate up to the search box and type in the question. Each object seperate from the other. It is so easy to get in way over your head. Look for codes first. Point in that direction. The fact you had a bad water leak pushes toward corrosion culprits but first find Codes for electrical faults.
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Hotshot
Joined: Jan 2004
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From: St Louis
If the MIL isn't coming on, either the PCM isn't getting power or it's dead. You don't have a fuel pump problem, in other words, the problem is further upstream.
I'd suggest you verify 100% that the PCM is, in fact, getting its power otherwise you're going to stay lost in the weeds (where you are now),
I'd suggest you verify 100% that the PCM is, in fact, getting its power otherwise you're going to stay lost in the weeds (where you are now),
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Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
Seriously????
The battery saver relay has nothing to do with the PCM or the fuel pump relays. He has a 97. It has neither PATS nor does it have an HEC.
It's one thing to try to be helpful, it's quite a different situation when you don't have a clue how the system works.
The battery saver relay has nothing to do with the PCM or the fuel pump relays. He has a 97. It has neither PATS nor does it have an HEC.
It's one thing to try to be helpful, it's quite a different situation when you don't have a clue how the system works.
Fleet Owner
Joined: Mar 2012
Posts: 26,065
Likes: 4,145
From: Near Cal. Avenue
My sorry, you are correct, The PCM has its own relay. While the fuel pump has its relay. Fuses and power distribution maybe corrosion from his prior leakage. Swap in some good relays and look for corrosion on the old ones. The PCM has 2 paths of power, one constant for its memory, the other the relay. It should code if it constantly resets. I moved you up, up to a newer model truck offhanded, should have read the thread closer, rushed my thoughts. The newer models have a lot more diagnostics the owner can call on. LOL
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Cross-Country
Joined: Oct 2012
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Okay so since I determined the truck does have PATS or HEC... Now everyone is on the same page. Easiest way to determine if the ECM is getting power would be? And if it is getting power how can I check to see if it is it? Hook up a code reader to it? see what it says? I have seen things before say unable to connect, check cable and try again. Dont remember if I have saw it on this truck or not. But one topic at a time....
1. Best way to determine if the ECM is getting power
2. Can I check to see if it is a bad ECM before taking it to Ford? And how to determine if its bad or not?
1. Best way to determine if the ECM is getting power
2. Can I check to see if it is a bad ECM before taking it to Ford? And how to determine if its bad or not?
Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
You did check fuse F24 under the hood, didn't you? The whole system relies on it and fuse F30 which, if the PCM Power Relay energizes, is oklay.
Since your MIL doesn't come on, either the bulb is burned out or the PCM is not powering up. Therefore, you'll have to go to plan B(1) or B(2)
B(1) If you have a scan tool, see if it connects. If it does, the PCM is powering up. If it doesn't, either the PCM is not powering up of the OBDII port is not delivering vehicle power to the scanner (cigar lighter fuse, usually).
B(2) Disconnect the connector from the TPS, turn the ignition switch to RUN, and look for +5 volts between the Vref and the signal return wires of the harness connector (BRN/W // GRY/RD).
If you have +4.5-+5.5 volts, the PCM is powered up. If it reads zero, the PCM is not receiving power and you'll nee to go back and check the PCM input power.
PCMs do go bad, but not very often. Usually, it's something external to the PCM.
Since your MIL doesn't come on, either the bulb is burned out or the PCM is not powering up. Therefore, you'll have to go to plan B(1) or B(2)
B(1) If you have a scan tool, see if it connects. If it does, the PCM is powering up. If it doesn't, either the PCM is not powering up of the OBDII port is not delivering vehicle power to the scanner (cigar lighter fuse, usually).
B(2) Disconnect the connector from the TPS, turn the ignition switch to RUN, and look for +5 volts between the Vref and the signal return wires of the harness connector (BRN/W // GRY/RD).
If you have +4.5-+5.5 volts, the PCM is powered up. If it reads zero, the PCM is not receiving power and you'll nee to go back and check the PCM input power.
PCMs do go bad, but not very often. Usually, it's something external to the PCM.
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Cross-Country
Joined: Oct 2012
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Okay, well I attached the scan tool to it, self powered Matco scan tool, as soon as I plugged it in to the OBDII port it turned on, selected the vehicle I was connecting it to, and tried to connect to the ECM. It said there was a connection failure to check cables and try again, well I know that my cables are in good working order so Im assuming its not able to connect to the ECM. Im also going to assume that the TPS is Throttle Positioning Sensor? I will go try that right now since I still havent been able to figure it out. And you say with key in RUN i should get around 4.5-5.5 v? If the ECM has power going to it but the ECM is bad, will it still get voltage to it? I cannot access the pins or try and trouble shoot if im getting power directly at the plug for the ECM. Im going to assume time to take the truck to the dealer anyways right?
Fleet Owner
Joined: Mar 2012
Posts: 26,065
Likes: 4,145
From: Near Cal. Avenue
If you are not getting power, check the logical problem first. Either the Power distribution module or the connection at the PCM. Unplug an look for corrosion. Look for damage in the Fuse Box and a broken wire near the Puter. Reason is your former leak started corrosion and years of use finished it maybe. Look for a bad ground near your battery to the frame. Check the second path of power to the ECU for damage. Get a wire harness diagram to follow the route. If your lighter circuit is hot your OBD11 should connect. Too bad you can't do a HEC test to check your CANBUS. IF your tests ran thru the cluster the puter would probably be good. You wouldn't be the first to have had his fuse pulled, disabled OBDII port. Check your owners manual for fuse positions and relays and pop in a good one. LOL
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