DL1 & Dash2 - mileage recording error

[VinnieVX7]

I have a DL1 connected to a Dash2 and Emerald ECU via CAN bus in a Caterham. Speed on the Dash2 is supplied by GPS.

The Odometer over records mileage at a rate of almost exactly +20%.

In the car I also have a Terratrip 303plus. This shows speed and distance measured from a wheel sensor. The values for speed are virtually identical on both the Dash2 (GPS) and the Terratrip (Wheel sensor). The distance recorded is different by 20%.

Switching between miles and km makes no difference to the rate of the error.

How can that be?

[Support]

It is possible that there is a bug in the firmware which converts from the speed to the distance. This firmware hasn't changed for around 8 years, but that doesn't mean it can't be wrong. I am doing some work on the DASH2 firmware now so will take a look.

Martin

[VinnieVX7]

For what it's worth, the mileage recording has been fine for about two years after installation. I believe this over reading started at some point during this year. The car does not have the Terratrip computer installed permanently and so there wasn't anything to benchmark against and its not something I pay particular attention to usually. However, following a mapping session for the engine and on our way to participate in a rally style event we were measuring fuel and distance to see how the fuel economy had been affected. It was at this point that we picked up the discrepancy between the two measurements (Terratrip and Dash).

On previous events in 2013 and 2012 there was no discrepancy between the two measurements so "something" happened to it.

[Support]

Very odd. I have just checked on the firmware that I am working on, at a constant speed of 180mph 10 miles was clocked up in 3:22. Given the errors in my timing this certainly looks to be correct.

Martin

[VinnieVX7]

Dumb question: Is the odometer a function of the speed displayed. For example it's not possible for me to have configured the odometer to take it's input from something other than the speed displayed?

[Support]

The only way you could have something odd happening is if you have the speed configured to come from both the RS232 and from the internal sensor. If not then the distance is just calculated by adding up the speed values at regular intervals. It doesn't make any difference which speed source is used.

Martin

[VinnieVX7]

Returning to this issue:

The car has been stored over the winter and I've just got around to checking through everything. So, first of all, the issue persists and the ODO on the Dash2 continues to over read, speed however is accurate. I am comparing the ODO and speed figures with those displayed on my Terratrip 303plus.

Since last September I have:

1. Reflashed both the DL1 (200511) and Dash2 (130514) to the latest version.

2. Checked the config of the Dash2 and confirmed that only one source (RS232) is used. Yes, and this was always the case.

3. Reconfirmed that the ODO v. Terratrip data is over reading by 20%. The speed has been cross checked with a separate GPS source and is identical on three devices: Terratrip, TomTom and Dash2 display. Distance is identical on TWO devices Terratrip and TomTom. 20% higher on Dash2....

Current config is DL1 Mk2 with a GPS antenna
Emerald ECU data fed by CAN bus interface
Dash 2 using RS232 for speed