97 E450 PSD E4OD trans/speedo problem

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Apr 3, 2004 | 08:37 PM

Twillmann

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97 E450 PSD E4OD trans/speedo problem

Lately I have had a weird problem that even Ford cant figure out. I will be running down the road, the speedometer will drop to zero, and the transmission will start cycling in and out of gears. If you let you foot off the gas, the speedo returns and the trans shifts into OD, but as soon as you hit the gas, it happens again. We have replaced the vehicle speed sensor in the rear end, and the PCM. This happens sometimes once a week, sometimes 2 or 3 times a day?
I have read posts about the PSOM going bad, but this truck has a mechanical odometer. Where is the PSOM located?

Any ideas?

Thanks
Todd

Last edited by Twillmann; Apr 3, 2004 at 09:17 PM.

Apr 4, 2004 | 12:27 PM

Twillmann

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Bringing this back to the top, I really need some ideas you PSD experts.

Thanks Again
Todd

Apr 4, 2004 | 08:54 PM

78fordman

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From: Jefferson, Iowa

I'm pretty sure you have an electronic speedo. Well it sounds like something is shorting out. Make sure the TPS sensor is not shorting out, check the grounds also.

Jul 31, 2004 | 01:14 AM

Aldenh

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Quote:

Originally Posted by Twillmann

... and the transmission will start cycling in and out of gears ...

Did you get this problem resolved? I have a similair problem with my transmission cycling in and out of overdrive. Just wondering if you found a solution.

Alden

Jul 31, 2004 | 07:00 AM

Kwikkordead

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From: Rio Rico, AZ.

Just a shot in the dark here, but what about a poor ground connection? I heard somewhere that E4OD's would chew up some rear bushing due to current going through the body of the transmission in the wrong fashion due to inadequit grounding on the whole vehicle. Maybe run an extra wire from the body of the trans to the battery for an experiment.

Jul 31, 2004 | 11:30 AM

Aldenh

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I actually have a 4R100. But I will look at this and give it a try. I'll let you know if it makes a difference.

I'm going from memory here, but I believe the trouble codes I read last night were P0500 and P0443. I wrote them down, but I don't have my notebook with me right now.

Thanks for responding,
Alden

Jul 31, 2004 | 08:39 PM

Twillmann

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I replaced section of wiring harness that runs over the top of the tranny and the problem went away. Ford wrapped heat shield around it so I think they know they have a problem there.

Thanks
Todd

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Aug 16, 2004 | 01:23 AM

Aldenh

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Quote:

Originally Posted by Twillmann

I replaced section of wiring harness that runs over the top of the tranny and the problem went away. Ford wrapped heat shield around it so I think they know they have a problem there.

Thanks
Todd

Well, it took a while, but I found my problem. The two wires from the OD button to the PCM were shorted together somewhere underneath the coach. I ran some temporary wires, and it runs like a dream!

Thanks for the help.

Alden