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1999 F-250 Superduty 7.3
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Discussion Starter · #1 ·
Need help just rebuilt the motor and installed it now a few of the cluster lights light up dim with no key in the ignition, also when you turn the key on there is no wait to start light and no fuel being pumped. I checked the fuses and the there are three that light dim with no key in the ignition one of them is for the PCM, did I miss a ground somewhere, hook something up wrong? I never disconnected the GPR or the IHR when i took the wiring harness off so they should all still be hooked up correctly. Anybody have any ideas?
 

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Remember, that both the Fuel Pump and the GPR are controlled by the PCM. If you have no WTS light then it sounds like the PCM isn't running so neither are going to work.

More info, what Year?
What happened to the old motor?
Was it the Same year motor?
Did you drive it with the old motor so you know you're not dealing with an existing condition?
 

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1999 F-250 Superduty 7.3
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4 Posts
Discussion Starter · #3 ·
Remember, that both the Fuel Pump and the GPR are controlled by the PCM. If you have no WTS light then it sounds like the PCM isn't running so neither are going to work.

More info, what Year?
What happened to the old motor?
Was it the Same year motor?
Did you drive it with the old motor so you know you're not dealing with an existing condition?
Late 99 old motor had a hole between the cylinder wall and water jacket, rebuilt the same engine I took out, was running and driving before engine was pulled never had this problem before.
 

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OK so yea, this is probably a wiring issue. But I would think, that if you have Low Voltage at the fuse (that "dim" PCM fuse) then it's about Supply not Ground. The PCM doesn't run right much under 10v (use a meter not a test light), find out where the loss is in supplying the fusebox...
 

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1999 F-250 Superduty 7.3
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Discussion Starter · #5 ·
OK so yea, this is probably a wiring issue. But I would think, that if you have Low Voltage at the fuse (that "dim" PCM fuse) then it's about Supply not Ground. The PCM doesn't run right much under 10v (use a meter not a test light), find out where the loss is in supplying the fusebox...
I am “guessing” it a ground issue as I have low voltage at the fuse when the key if off and out of the ignition. Or should there be a constant power at the PCM fuse when the key is off and out of the ignition
 

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Yea but,,, with a Test light, it has a different ground that anything else ;)

Most of the fuses have power all-the-time and the PCM certainly does (although it gets power from several sources). No fuse, with a properly grounded meter/light, should have less than battery voltage at it. Somewhere between the battery and the fusebox there's a problem...
 

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1999 F-250 Superduty 7.3
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Discussion Starter · #7 ·
Yea but,,, with a Test light, it has a different ground that anything else ;)

Most of the fuses have power all-the-time and the PCM certainly does (although it gets power from several sources). No fuse, with a properly grounded meter/light, should have less than battery voltage at it. Somewhere between the battery and the fusebox there's a problem...
Ok I will check I won’t get back to it for a couple days but I will update when I do
 
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