First off This is in reguards to a 2004 Ram 1500 4x4 QC 5.7L. Using a 3815 Fully updated flashpaq.

I had the problem before I purchased my flashpaq. Although I purchased the flaspaq in hopes it would fix my problem. I am hoping someone here may be able to help or point me in the right direction.

Problem: Speedometer is 10Mph off (only the speedometer). For example reads 25 when I am doing 35. I verified the speed is off with another car pacing me.

Known facts that might help:
1. Recently Purchased truck used
2. Had a stock flash in the ECM (flashpaq recognized it)
3. Running stock size tires and rims ( I have the build sheet )
4. Verified the correct tire measurements are installed
5. Odometer is running correct (door locks lock at 5Mph not the 15mph the manual says and cruise control can engage 10Mph sooner than it should) 10mph off.
6. I dont know if any gears have been changed (If that could make a difference)
7. The only error codes I found when I hooked flashpaq were for 3 secondary coils and EGR postion sensor high.


Again, Any help or info from people familiar with this problem or can tell how only my speedo can be off but not my odometer, Gas mileage, point at wich door locks engage and cruise control engage.

Thanks

 

Changing gears will not make any difference. If your tire size is loaded in the handheld as stock and that they are, then you may want to look into your speed sensor or the possibility you may need a new speedo unit/??

 

Where would the speed sensor be located? The Rearend or in the tranny? Also Could it be possible for an incorrect sensor be installed and cause the problem?

Thanks

 

trans. & i don't think that's possible or would have any effect other than just not work.

 

My speedo was also messed up when I got my '05.it was 8 M.P.H off.I found this out when I was doing what i thought was 70 and a real nice DPS officer decided to pull me over and let me know i was doing 78.Luckily I only got a warning.I bought an SC3815 to try to fix the problem but it only got it close.I had to go to the dealer.Come to find out my speedo was set for 17's and not the 20's I had.they had to set the speedo back 2 nocthes.(what ever that means)They told me that reflashing the comp won't fix it.It still was off about 3 M.P.H. (i tracked it with my gps)The 3815 fix it the rest of the way.

 

Thanks for the replies Dirtydog.

Just an update...I took the truck out and used the datalog feature of the flashpaq and it was reading the correct speed while the speedometer stayed 10mph faster.

So the trucks computer deffinetly knows the correct speed. That explains why the doors lock at what the speedo says is 5mph and not 15mph and why the Cruise Control can engage 10Mph less than what it should.

I dont understand (please correct me if I am wrong) the computer would get a signal from the sensor and interpret that to the speedo. But my thinking must not be right since the computer does know the correct speed and displays that on the Flashpaq.

 

good info.

 

Thanks! I will look into that. It could very well be the culprit. I know there was a recall on this truck and other year trucks about the tire size sticker being incorrect (mine reads 15's) but came with 17's. I would think that maybe it was possible the speedo might have been incorrectly setup as well.

 

Well with the previous info from "rtmtrrdr" and what I knew of the Tire sticker recall. I thought I would check how the size difference of what the sticker says versus what came stock on the truck.


I used the tire comparrison calculater at 1010tires. Top is what sticker says (not even an option on this truck). Bottom is what the build sheet says and what I am running. Almost an 8mph difference. I wonder what it is in the spedometer that the dealer "set back two notches" for you "rtmtrrdr". Obviously there is more to calibrating some speedometers than just the computer.

Overall Diameter: 6.85 in 681.99 mm

Sidewall Height: 5.92 in 150.36 mm

Radius: 13.42 in 340.86 mm

Circumference: 84.35 in 2142.4 mm

Revs per Mile: 774.6
Actual Speed: 60 mph 100 km/h

Speedometer Difference: -
Diameter Difference: -

Tire 1 - 245/70R17 >Search Tires

Section Width: 9.64 in 245 mm

Rim Diameter: 17 in 431.8 mm

Rim Width Range: 6.5 - 8 in

Overall Diameter: 30.50 in 774.7 mm

Sidewall Height: 6.75 in 171.45 mm

Radius: 15.25 in 387.35 mm

Circumference: 95.81 in 2433.5 mm

Revs per Mile: 681.9

Speedometer1: 52.8 mph 88.0 km/h

Speedometer Difference: 13.59% too slow
Diameter Difference: 11.97%

Thanks Again. I will post what I find out.