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Speaking of 2 button traveler problems..

614 Views 1 Reply 2 Participants Last post by  Mangelhaft
'89 Lebaron Convertable T1 / automatic, California emmisions. My traveler is consistently telling me that I am getting better mpg's than the actual math tells me that I am getting. The math says I am getting near 21mpg's and the traveler says anywhere from 27 and up avg mpg's. How accurate are they, how do they actually get the info, what info do they use?
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The later traveler/trip computer modules recieve their data from two sources: the CCD data buss, and the fuel tank level sensor. The CCD buss passes the speed sensor and fuel usage data. This data is manipulated by the programming of the traveler's MPU to calculate the fuel economy data. It uses the fuel economy data and the fuel tank level data to calculate the distance to empty.

The earlier traveler/trip computer modules do not use the CCD buss. They get their fuel usage data directly from the ECU. They also have inputs for the speedometer and fuel tank level. They use this data, in a similar fashion as the later traveler/trip computer modules, to calculate all of their data.

The later traveler/trip computer modules that have more than the ECON, TRIP, DTE, and elapsed time, get some of their data from the BCM, also.

From my research into the various traveler/trip computer/navigator modules, the ones which are connected to the CCD buss tend to be the most accurate.

When I put thr traveler in my '93 Spirit, I was interested in the accuracy. I compared the traveler data (pulled the connector on the back for a "hard reset" effect), with the calculated data from a full tank of fuel and the odometer. It was on a trip to Washington DC, so the driving was pretty steady. The traveler was off by 1.75%.

I have not done a ROM dump on the traveler MPUs to figure out the programming. If anybody has the capability to read Motorola 68HC05 and 68HC11 MPUs, I am willing to send them the ICs.
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