Can't connect to PCM
09-27-2010, 08:51 PM
#11
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You nailed it....the light bulb was burned out! However, I have replaced it and it still doesn't come on...I get brake, ABS, but no check engine light. Is there no way to test a computer to see if it's good? Can't find a friend with 1996 f-150 to swap computers...Thinking at this point I need to beg a running truck off Craigslist! I have checked all the + and - points on the harness to the computer and they all seem to check out....I used this diagram as the link on Ford Fuel injection only seems to go to 1995....
09-28-2010, 01:05 AM
#13
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Thanks for the input, it was glaring at me and I didn't pick up on it since I did the search for a 5.0...as you can tell, with electrical I'm lost...anyone got a diagram for a 5.0 since I can't seem to find one on the forum or google?
09-28-2010, 02:02 AM
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The computer is programmed when to open fuel injectors in relation to the valve timing from PIP. Without it working properly (PIP), and the signal passing through the TFI to the ECU, the computer never senses the engine moving.
You have no spark w/ the Spout plug in. Spark returns when spout plug is removed. Spout plug removal bypasses /ECU influence on the ignition system via the TFI.
The moral of the story is, take your TFI module in & have it checked!
You have no spark w/ the Spout plug in. Spark returns when spout plug is removed. Spout plug removal bypasses /ECU influence on the ignition system via the TFI.
The moral of the story is, take your TFI module in & have it checked!
Last edited by ymeski56; 09-28-2010 at 02:09 AM.
09-29-2010, 11:46 PM
#18
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Ok...First Thanks for the continued help and ideas of what to look for, but I took the TFI in and it checks out.....
I didn't think that was going to be the issue since the fuel relay doesn't seem to be engaging but it was worth a shot...Is there any other info or tests I could do to give you a better picture of what's going on??
09-30-2010, 12:11 AM
#19
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Ok...First Thanks for the continued help and ideas of what to look for, but I took the TFI in and it checks out.....
I didn't think that was going to be the issue since the fuel relay doesn't seem to be engaging but it was worth a shot...Is there any other info or tests I could do to give you a better picture of what's going on??
I didn't think that was going to be the issue since the fuel relay doesn't seem to be engaging but it was worth a shot...Is there any other info or tests I could do to give you a better picture of what's going on??
I think it's the PCM relay, enough that I'd go to the bone yard & grab some to switch out w/. I'd also grab a couple f/p relays. they are not interchangeable though. The PCM relay has a small resister built into it to protect the ECU. That's why they're color coded. I've popped the covers off them w/ a small screw driver before to inspect the contacts & observe function. two opposing sides have clips built into the covers. One of the cover didn't re-secure completely, so i wrapper electrical tape around it. Still working.
Last edited by ymeski56; 09-30-2010 at 12:20 AM.
09-30-2010, 12:35 AM
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Their are multiple contacts for multiple circuits in the PCM relay. Just because the relay pulls in, doesn't mean all the contacts are completing. The circuit for the fuel pump relay runs through it. Is there power to the F/P relay circuit from the PCM relay when PCM is energized? Does the F/P relay pull in?
I think it's the PCM relay, enough that I'd go to the bone yard & grab some to switch out w/. I'd also grab a couple f/p relays. they are not interchangeable though. The PCM relay has a small resister built into it to protect the ECU. That's why they're color coded. I've popped the covers off them w/ a small screw driver before to inspect the contacts & observe function. two opposing sides have clips built into the covers. One of the cover didn't re-secure completely, so i wrapper electrical tape around it. Still working.
I think it's the PCM relay, enough that I'd go to the bone yard & grab some to switch out w/. I'd also grab a couple f/p relays. they are not interchangeable though. The PCM relay has a small resister built into it to protect the ECU. That's why they're color coded. I've popped the covers off them w/ a small screw driver before to inspect the contacts & observe function. two opposing sides have clips built into the covers. One of the cover didn't re-secure completely, so i wrapper electrical tape around it. Still working.