Speedometer Issues
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Speedometer Issues
I am looking for help on figuring out which computer I needto replace on my 1999 F250 4X4 Super Duty 7.3L Diesel truck. Here is the backstory. The light on the overdrive is blinking and the speedometer is goingback-n-forth when driving above 20mph. I took it in to get looked at and they replacedthe speed sensor on the rear axle and another sensor near the transmission. Themechanic told me after changing both of those sensors nothing changed andthinks that most likely the computer is the problem. Then said I need to takeit to ford for more details. I am not taking it to ford...too much money spentgoing there. I was told there are several computers in the truck and I don’thave a diagram or schematics to look at to figure out which computer to replaceor to even know if there are several computers…so on. If someone could tell mewhich computer to replace or point me in the right direction, would be nice. Thanks.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
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Posting Guru
Joined: Oct 2008
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There is only one PCM, a Transmission Solenoid Pack, and Generic Electric Module. What you are describing is the Transmission Control Indicator Lamp (TCIL).
Do you have a way to view codes? One which will also identify Codes from the Transmission Control Indicator Lamp (TCIL).
What you describe is indicative of the speed sensor at the rear axle. You say you have had that replaced. It perhaps may be in the wiring, or a corroded connection.
Do you have a way to view codes? One which will also identify Codes from the Transmission Control Indicator Lamp (TCIL).
What you describe is indicative of the speed sensor at the rear axle. You say you have had that replaced. It perhaps may be in the wiring, or a corroded connection.
Thread Starter
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New User
Joined: Nov 2014
Posts: 2
Likes: 0
There is only one PCM, a Transmission Solenoid Pack, and Generic Electric Module. What you are describing is the Transmission Control Indicator Lamp (TCIL).
Do you have a way to view codes? One which will also identify Codes from the Transmission Control Indicator Lamp (TCIL).
What you describe is indicative of the speed sensor at the rear axle. You say you have had that replaced. It perhaps may be in the wiring, or a corroded connection.
Do you have a way to view codes? One which will also identify Codes from the Transmission Control Indicator Lamp (TCIL).
What you describe is indicative of the speed sensor at the rear axle. You say you have had that replaced. It perhaps may be in the wiring, or a corroded connection.
The mechanic ran the codes and the code that came up was forthe speed sensor.
I have never delt with wiring on vehicles much less a truck. How hard will it be to follow where the wiring goes and replace the wiring?
Posting Guru
Joined: Jan 2013
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From: North Lake Tahoe
Is your truck an Early 99 or late 99. My truck went through a similar problem and it was where I tied the ground for some driving lights. You need to check that ground and clean it before spending money on new computers and such. It is the green wire that grounds the ABS system (not sure about later models but the E99). If not grounded properly it will throw iff your transmission shifts as well as your speedo. My tranny light was flashing as well but might have been a separate issue if I remember correctly.
In the pic you can also see the computer (white box with the 4 wires going into it) just in front and below the driver side battery.
Hopefully its this simple as I got lucky. Found loose ground after I bought the new computer.
In the pic you can also see the computer (white box with the 4 wires going into it) just in front and below the driver side battery.
Hopefully its this simple as I got lucky. Found loose ground after I bought the new computer.
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