Shifting problem with Triton V10 and 4R100


Old 07-17-04, 03:46 PM
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Shifting problem with Triton V10 and 4R100

I have an RV that had a Triton V10 and transmission put in it in 1999. It subsequently had the transmission replaced in 2002.

Now it's got a problem where it runs great through all the gears except when it hits overdrive. It won't stay in OD. It cycles in and out at about 1 to 2 second intervals.

I've had a Ford dealership look at it, and they say the transmission is in great shape. They believe it is an electrical problem. But they didn't want to work on it because it is a "non-standard" installation.

Has anyone experienced a similiar problem or have a suggestion on where I should start looking?

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Old 07-18-04, 06:11 AM
Join Date: Apr 2002
Location: Pittsburgh,Pa
Posts: 2,417
I would suggest an rv dealer/repair facility drive it and advise you.This could be something common only to your combo and the Ford dealer may not have the answer.If it does this on a level road at a steady throttle position something is wrong,if you are on hills or pulling a hilll it may be normal at that throttle position,you could try driving at a higher or lower speed.Maybe there is some type of reflash for the powertrain control module.Good luck.
Old 07-18-04, 06:31 PM
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Thanks for the reply. It happens every time it hits OD. Flat, downhill, uphill, it doesn't seem to make a difference.

I've talked to the guy who did both the original conversion and replaced the transmission. He suggested that when they had a similar problem, the way they fixed it was by making sure the engine harness, transmission harness, computer, and air intake were all for the same year, in this case 2002.

I also talked to a guy from a shop locally who had a similair experience with a 4r100 transmission on an F250 truck. He said it took two good transmissions before they figured out that there was a problem with the transmission harness plug (??). He claimed that Ford had some problems with those harness' early on.

Just to add to my problem, there are only a small number of these conversions out there. Probably less than 30. So finding someone who wants to work on it isn't easy.

Old 09-07-04, 01:09 PM
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Triton V10 OD problem

I have a 2003 Coachmen Mirada that has a V10. I had the gear vendors over/underdrive put in about a month ago by Campingworld. I had this same problem over the weekend. It's at the Campingworld location now being looked at. Did you resolve your issue? I'm waiting for Campingworld to call me about what they found. In may case, even though the OD was turned off, the OD light indicator on the column kept blinking on and off, but anything I went into OD (via gear vendors) it would cycle in and out every few seconds.
Only other issue I had was I lost the speedo. Most the time it didn't work or if it did it was all over the place
Old 09-07-04, 09:45 PM
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Yes, I fixed my problem. It was a short between the two wires from the OD switch to the PCM.

One of the wires is the momentary switch which, when the button is pressed, puts 12V to the PCM which tells it to change the state of the OD (turn it off or on). The second wire is always at 12V and at the PCM is switched to ground to illuminate the OD light when the OD is turned off.

In my case, with the two wires shorted together, the PCM was getting a continuous signal to change state of the OD. So once I was up to speed and into OD, the PCM was shifting in and out as fast as it could.

I had it at an auto-electric shop for a quite a while, but I finally had to pull it back and figure it out myself because they weren't making any progress on it. This coach is very ... unique in that it is a gas pusher originally built with a Ford 460, and then having a V10 put in. I had to get the schematics for a 2000 F-550 and then do quite a bit of comparison between the vehicle and the schematics.

You might want to go to the Ford Truck Enthusiest web page and do a seach on "overdrive light blinking" in their Forums. That's where I got a lot of good info. As I recall, most of the post I saw suggested the Vehicle Speed Sensor (VSS) or Output Shaft Speed Sensor (OSS) were the problem. I changed both of these originally because it seemed like the most likely cause and it was reletively inexpensive and easy to do. I didn't have the speedometer problem you have. But since the VSS output is what drives the speedometer, you might give that a serious look.

I appologize for not posting my resolution earlier, but I resolved it just days before our vacation and I didn't have time. But we put 3300 miles on it without the problem reappearing. So I think I got it.

Hope this helps you. And feel free to ask if you have more questions.


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