Transmission shifting issues & bouncing speedometer
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Trailering
Joined: Jun 2024
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Transmission shifting issues & bouncing speedometer
2002 E350 Super duty 5.4
Speedometer intermittently bounces and OD light on shifter will blink, transmission will not shift correctly or into correct gear range. When speedometer not bouncing and OD light not on transmission seems to shift fine. Only codes that showed up was for VSS speed sensors so I changed both, one on top of rear differential as well as on top of tail cone of transmission. I also checked ground straps, pull electric plugs from transmission to check and clean. I was wondering if the range selector (neutral safety switch) has anything to do with this or if anyone here can point me in the right direction because I am ready to lose my mind! Before anyone suggest to change the dash cluster I don't believe that has anything to do with it because I believe PSOM ended in 1998 or 99
Thanks for any help you can give me
Speedometer intermittently bounces and OD light on shifter will blink, transmission will not shift correctly or into correct gear range. When speedometer not bouncing and OD light not on transmission seems to shift fine. Only codes that showed up was for VSS speed sensors so I changed both, one on top of rear differential as well as on top of tail cone of transmission. I also checked ground straps, pull electric plugs from transmission to check and clean. I was wondering if the range selector (neutral safety switch) has anything to do with this or if anyone here can point me in the right direction because I am ready to lose my mind! Before anyone suggest to change the dash cluster I don't believe that has anything to do with it because I believe PSOM ended in 1998 or 99
Thanks for any help you can give me
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
There is only one VSS, not two. The one on the trans has nothing to do with the speedometer or the vehicle speed that the PCM is looking at.
Your problem is the bouncing speedo signal. It could be a wiring problem between the VSS (located on the rear differential) and the PCM. It is also possible that there is a problem in the rear axle causing a problem.
The range sensor cannot affect the speedo.
And you're right, there is no PSOM on your truck.
Your problem is the bouncing speedo signal. It could be a wiring problem between the VSS (located on the rear differential) and the PCM. It is also possible that there is a problem in the rear axle causing a problem.
The range sensor cannot affect the speedo.
And you're right, there is no PSOM on your truck.
Thread Starter
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Trailering
Joined: Jun 2024
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There is only one VSS, not two. The one on the trans has nothing to do with the speedometer or the vehicle speed that the PCM is looking at.
Your problem is the bouncing speedo signal. It could be a wiring problem between the VSS (located on the rear differential) and the PCM. It is also possible that there is a problem in the rear axle causing a problem.
The range sensor cannot affect the speedo.
And you're right, there is no PSOM on your truck.
Your problem is the bouncing speedo signal. It could be a wiring problem between the VSS (located on the rear differential) and the PCM. It is also possible that there is a problem in the rear axle causing a problem.
The range sensor cannot affect the speedo.
And you're right, there is no PSOM on your truck.
IS it possible if the transmission is over full of fluid that could cause pressure issue and cause shifting issues?
Reason I ask is because when I was in hospital for my surgery one of the kids that works for me added fluid thinking it was low and over filled it badly....I took care of that but not sure if that could have caused any type of issues
Last edited by J.Civ; Jun 25, 2024 at 08:36 PM.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
Great!
Electrically speaking, how is the wiring between the PCM and the VSS? Does it have continuity? High resistance? Short to power? Short to ground?
No, that can't cause this.
Electrically speaking, how is the wiring between the PCM and the VSS? Does it have continuity? High resistance? Short to power? Short to ground?
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Trailering
Joined: Jun 2024
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I'm trying to find someone that can do this type of diagnostics for me, I don't have the tools or enough experience with wiring to give definitive answers to those questions. While I'm waiting for answers to those questions is there anything else you can think of that I should be checking?
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Trailering
Joined: Jun 2024
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Ok thanks!
I'm going to assume by your response the tone ring in the rear is such a long shot of being bad you're feeling that would be a last resort?
I'm going to assume by your response the tone ring in the rear is such a long shot of being bad you're feeling that would be a last resort?
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
Yes, the tone ring rarely fails.
One other thing that could be the cause would be a failed diode in the alternator. This would produce an AC ripple in the DC current. The PCM can read this as a speed input and cause the bouncing speedo.
The only way to know if this is happening is to put an oscilloscope on the output of the alternator. That's not a tool that most DIY people have. Most shops don't have one, either.
One other thing that could be the cause would be a failed diode in the alternator. This would produce an AC ripple in the DC current. The PCM can read this as a speed input and cause the bouncing speedo.
The only way to know if this is happening is to put an oscilloscope on the output of the alternator. That's not a tool that most DIY people have. Most shops don't have one, either.
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Cargo Master
Joined: Sep 2012
Posts: 2,112
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From: Eastern TN
Where is the tone ring in the diff? Input pinion, crown gear?
I heard there are handheld charging system testers that can check diodes in the car. See if an auto parts store with free charging system testing service has a diode test. Intermittent failure might be a problem.
Sixto
07 E350 5.4 198K miles
I heard there are handheld charging system testers that can check diodes in the car. See if an auto parts store with free charging system testing service has a diode test. Intermittent failure might be a problem.
Sixto
07 E350 5.4 198K miles
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
Look at the vehicle speed sensor mounted on the rear differential. If you pull that sensor out and look in the hole you'll see the tone ring. That's the part that the VSS looks at,
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Trailering
Joined: Jun 2024
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I know this is a longshot but on the idea of an electrical issue such as a bad diode could it be possible that the "adaptive learning strategy" needs to be cleared? The reason I asks is because the van sat for about 8 months at my job site and when I went to take it in for emissions testing the battery was dead, I jump started it and took it to emissions which it passed but that was the first time I noticed the shifting issues along with the bouncing speedometer and the blinking TCIL
Just a thought even though it's a total longshot.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
The adaptive strategy can't make the speedo bounce. The bouncing speedo is causing your shift issues. It is more likely to be a dirty windshield causing your issue than the adaptive strategy.
And when the battery was dead the adaptive strategy was cleared.
And when the battery was dead the adaptive strategy was cleared.