Edge and Gears
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Senior Member
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From: Tustin / Irvine CA
Ok then...... Adam06Fx4 must not be a very good tech.... I wouldn't want him working on my truck.
Anyways, do what would you guys suggest still for correcting the speedo?
I have tried entering a shorter tire in my Edge to trick it, and it seems to help. I guess I can go shorter until my speedo reads correctly. Right now, I have a 2350 tires circumference.
I did load previous settings and they settings I entered before showed up, so it looks as though the Edge is holding the setting. I will try a shorter tire and see what happens.
Anyways, do what would you guys suggest still for correcting the speedo?
I have tried entering a shorter tire in my Edge to trick it, and it seems to help. I guess I can go shorter until my speedo reads correctly. Right now, I have a 2350 tires circumference.
I did load previous settings and they settings I entered before showed up, so it looks as though the Edge is holding the setting. I will try a shorter tire and see what happens.
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From: Tustin / Irvine CA
I have programmed in a 24.5" tall tire and it is still off. It doesn't seem to be making much a difference if any at all, and Edge has not been much help.
Does anybody have a truck with 4:56's and 35's with an edge..... what are you using?
JD790,
Is your truck re-geared?
Does anybody have a truck with 4:56's and 35's with an edge..... what are you using?
JD790,
Is your truck re-geared?
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From: Western NC
Originally Posted by JD790
Agreed. Here is what oasis says:
Speedometer
The instrument cluster (IC) receives the vehicle speed sensor (VSS) signal from the PCM over the communication network. The PCM receives the VSS signal from the output shaft speed (OSS) sensor. The PCM monitors the VSS input and sends it to the instrument cluster (IC) over the communication network. With the VSS input, the instrument cluster (IC) provides the speedometer with a corresponding pointer movement.
The VSS:
is gear driven by the transmission.
sends a signal to the PCM indicating vehicle speed.
Output Shaft Speed (OSS) Sensor
The output shaft speed (OSS) sensor is a magnetic pickup, located at the output shaft ring gear, that sends a signal to the PCM to indicate transmission output shaft speed. The OSS is used for torque converter clutch control, shift scheduling and to determine electronic pressure control.
So in my mind, if you change gear ratio's, the output shaft speed WILL change due to the different gear ratio - thus changing your speedometer calibration, which is why you have to recalibrate the pcm to the correct gear ratio to keep your speedometer accurate.
The tone ring is going to spin at the exact same speed whether you have a 3.55, 3.73, 4.10, 4.56, 4.88, etc. etc. But, the engine speed (rpms) will be different due to the fact that the driveshaft rotations have changed due to the different gear ratio. If the driveshaft speed has changed, so has the output shaft speed, which will affect the speedometer.
If the speedo got its signal from the tone ring, then changing gears would not affect it. But it gets it from the OSS, so yes, gears will change your speedo until it is recalibrated.
Speedometer
The instrument cluster (IC) receives the vehicle speed sensor (VSS) signal from the PCM over the communication network. The PCM receives the VSS signal from the output shaft speed (OSS) sensor. The PCM monitors the VSS input and sends it to the instrument cluster (IC) over the communication network. With the VSS input, the instrument cluster (IC) provides the speedometer with a corresponding pointer movement.
The VSS:
is gear driven by the transmission.
sends a signal to the PCM indicating vehicle speed.
Output Shaft Speed (OSS) Sensor
The output shaft speed (OSS) sensor is a magnetic pickup, located at the output shaft ring gear, that sends a signal to the PCM to indicate transmission output shaft speed. The OSS is used for torque converter clutch control, shift scheduling and to determine electronic pressure control.
So in my mind, if you change gear ratio's, the output shaft speed WILL change due to the different gear ratio - thus changing your speedometer calibration, which is why you have to recalibrate the pcm to the correct gear ratio to keep your speedometer accurate.
The tone ring is going to spin at the exact same speed whether you have a 3.55, 3.73, 4.10, 4.56, 4.88, etc. etc. But, the engine speed (rpms) will be different due to the fact that the driveshaft rotations have changed due to the different gear ratio. If the driveshaft speed has changed, so has the output shaft speed, which will affect the speedometer.
If the speedo got its signal from the tone ring, then changing gears would not affect it. But it gets it from the OSS, so yes, gears will change your speedo until it is recalibrated.
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Originally Posted by JackandJanet
Your PCM may "think" your tires are bigger than they really are. Did you account for "squish"? Bill recommends reducing the actual tire circumference by 3%, and in my case at least, this was just about right.
- Jack
- Jack
I tried that once and it threw my numbers off. I went back and did the calculations per the Edge manual and my speedo was dead on at 80mph with GPS.
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From: Tustin / Irvine CA
Originally Posted by clar
......well almost everyone..
I have already sent a PM to Bill, so I will wait until he returns. From what everyone says, it sounds like he will be the best person to talk to and knows these programmers back and forth.
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From: Lincoln, Nebraska
Originally Posted by street3285
JD790,
Is your truck re-geared?
Is your truck re-geared?
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get with the times...i pitty the ppl who bring there vehicle to you old school techs...
Beginning in 1998, the Vehicle Speed Sensor (VSS) has been deleted from Ford truck models. On vehicles equipped with 4-Wheel Anti-Lock Brake Systems (4WABS) , the vehicle speed signal is generated by the rear anti-lock brake sensor and sent to the 4WABS module. The 4WABS module sends the vehicle speed signal to all systems which require a vehicle speed signal input.
Vehicle Speed Sensor (VSS) is located on the rear differential.
Vehicles equipped with Rear Anti-lock Brakes (RABS) generate a vehicle speed signal from the rear axle speed sensor. The Generic Electronic Module (GEM) receives this signal (VSS_GEM) for internal use and then distributes it to the appropriate other users, i.e., the PCM, speed control module, and speedometer.
Beginning in 1998, the Vehicle Speed Sensor (VSS) has been deleted from Ford truck models. On vehicles equipped with 4-Wheel Anti-Lock Brake Systems (4WABS) , the vehicle speed signal is generated by the rear anti-lock brake sensor and sent to the 4WABS module. The 4WABS module sends the vehicle speed signal to all systems which require a vehicle speed signal input.
Vehicle Speed Sensor (VSS) is located on the rear differential.
Vehicles equipped with Rear Anti-lock Brakes (RABS) generate a vehicle speed signal from the rear axle speed sensor. The Generic Electronic Module (GEM) receives this signal (VSS_GEM) for internal use and then distributes it to the appropriate other users, i.e., the PCM, speed control module, and speedometer.
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From: Western NC
The ABS module uses the wheel speed sensors and rear axle speed sensor. Unplug the wheel speed sensors and go for a drive, wait, the speedometer still works, woah thats crazy!!! And that diagram is from a mid 90's F-150, they haven't used the 5.8/7.5L since '96. Your truck has a OSS sensor, hook it up to the scan tool and look. That above is a definition from OASIS on *Current* vehicles. A gear change will throw off the speedometer period, end of story. *My bad the 5.8/7.5 lists as a 8600lb+, so its the 250&350, and they ran until 98.*
Last edited by joshmac4.6; Apr 3, 2008 at 02:52 PM.