2002 7.3 Throttle Response Problems
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Yeah... I'm pretty sure that can't hurt. Is it auto-ranging (no need to change the min/max ranges)?
I fear this is pretty basic, as the Accelerator Position Sensor hooks directly to the PCM. If the reference voltage is there, the ground is there, and the output to the PCM varies - there's not much left other than the PCM or a broken wire. That ground reading does look pretty hinky, though. I'd follow that ground wire to find out where the ground is supplied, and make sure it's not corroded or loose.
I fear this is pretty basic, as the Accelerator Position Sensor hooks directly to the PCM. If the reference voltage is there, the ground is there, and the output to the PCM varies - there's not much left other than the PCM or a broken wire. That ground reading does look pretty hinky, though. I'd follow that ground wire to find out where the ground is supplied, and make sure it's not corroded or loose.
Thread Starter
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New User
Joined: Jul 2016
Posts: 16
Likes: 0
Your thoughts?
Yeah... I'm pretty sure that can't hurt. Is it auto-ranging (no need to change the min/max ranges)?
I fear this is pretty basic, as the Accelerator Position Sensor hooks directly to the PCM. If the reference voltage is there, the ground is there, and the output to the PCM varies - there's not much left other than the PCM or a broken wire. That ground reading does look pretty hinky, though. I'd follow that ground wire to find out where the ground is supplied, and make sure it's not corroded or loose.
I fear this is pretty basic, as the Accelerator Position Sensor hooks directly to the PCM. If the reference voltage is there, the ground is there, and the output to the PCM varies - there's not much left other than the PCM or a broken wire. That ground reading does look pretty hinky, though. I'd follow that ground wire to find out where the ground is supplied, and make sure it's not corroded or loose.
can I just add a splice and re-ground the wire?
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New User
Joined: Jul 2016
Posts: 16
Likes: 0
no blow fuses
There are no blown fuses and the gauges are working, thanks for the help
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Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
This is just me, but I'd fix a ground before I complicate matters with splices and added wires. Adding stuff is the first step in making a "What the hell is going on here?" truck.
Junior User
Joined: Sep 2003
Posts: 77
Likes: 0
From: Quinton,VA
I had just about the same problem. Do you have adjustable pedals? Mine are and I had to replace the entire pedal assy because the tps is not removable from the pedal assy. If you have to replace the pedal assy, don't go cheap. Buy the Motorcraft or whoever makes it for them.
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New User
Joined: Jul 2016
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already replaced pedal 2 times
I had just about the same problem. Do you have adjustable pedals? Mine are and I had to replace the entire pedal assy because the tps is not removable from the pedal assy. If you have to replace the pedal assy, don't go cheap. Buy the Motorcraft or whoever makes it for them.
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New User
Joined: Jul 2016
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Replace the PCM?
If all the readings are ok and the grd wire checks out. Then is it the PCM?
Lead Driver
Joined: Jun 2004
Posts: 6,311
Likes: 578
From: Amarillo, TEXAS!
Yes, if you're sure all the readings are right, then the next step is the PCM. It would be nice if you could get your hands on a known good one to test with. Do you know anyone with a similar truck who might let you try theirs? I'm not sure if it needs to be the same year or PCM family for testing or not, but there are several people here who would have the specifics on that.
Logistics Pro
Joined: Aug 2009
Posts: 3,609
Likes: 324
From: Arizona
Wait, in post #15 he is showing he got about 25 ohms of resistance on the ground wire, that is too much, the PC will only see a tiny fraction of the voltage with that much resistance in the circuit.
Last edited by bigb56; Jul 19, 2016 at 07:53 AM. Reason: To remove incorrect information
Logistics Pro
Joined: Aug 2009
Posts: 3,609
Likes: 324
From: Arizona
The vref is shared on that harness with the MAP, EBPS, ICP sensor and the cam sensor. But if you have a solid 5V on the brown/white KOER then that should be OK. If not try unplugging each of these sensors one at a time to see if the 5V comes back.
1. Do you have battery voltage at the red/yel wire (KOEO)
2. Can you unplug the TP sensor and check for 4 to 6 volts when measuring between the brown/white and the yellow/white on the connector with the key on? Don't measure between the brown/white and chassis ground, measure between the brown/white and the yellow white. Post back the results and we'll go from there.
Would hate to see you buy a new PC before verifying the integrity of the wires and connections.
1. Do you have battery voltage at the red/yel wire (KOEO)
2. Can you unplug the TP sensor and check for 4 to 6 volts when measuring between the brown/white and the yellow/white on the connector with the key on? Don't measure between the brown/white and chassis ground, measure between the brown/white and the yellow white. Post back the results and we'll go from there.
Would hate to see you buy a new PC before verifying the integrity of the wires and connections.
Last edited by bigb56; Jul 19, 2016 at 07:55 AM. Reason: corrections