Gauges and TCM issues.
07-09-2019, 07:38 PM
#32
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Join Date: 04-08-2008
Location: Lacombe, LA
Posts: 131
I checked the CAN bus resistance with the battery disconnected.
The two resistors are in parallel , therefore you divide the two values and get 60 ohms. If in series, you would add the values.
I did a 10 minute road test this evening and check the battery voltage after 20 minutes and got 12.5 volts.I think this battery is going back this weekend and being replaced with a different brand.
The two resistors are in parallel , therefore you divide the two values and get 60 ohms. If in series, you would add the values.
I did a 10 minute road test this evening and check the battery voltage after 20 minutes and got 12.5 volts.I think this battery is going back this weekend and being replaced with a different brand.
07-10-2019, 09:28 AM
#34
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Join Date: 08-03-2010
Location: Lake Ronkonkoma, N.Y.
Posts: 3,564
I get a code U0073 or U0100 when it is hot out and the windows are closed in the car. This is a random thing.
When I get in I have to open the windows that's how hot it can feel inside.
I haven't measured the values of the Can bus at the ODB port when this happens because of the pain to disconnect the battery.
When you originally tested the two wires at the port did you see a resistance value different than when the battery was not disconnected ?
07-10-2019, 12:24 PM
#35
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Join Date: 04-08-2008
Location: Lacombe, LA
Posts: 131
The battery was purchased on 6/16/19. I saw reviews for all the Sam's Club batteries, but this size 47 had zero, hmm? My previous battery was a Diehard Gold that was 7 1/2 years old.
Not bad life for a Diehard, the one in my Jeep was 9 years old.
Not bad life for a Diehard, the one in my Jeep was 9 years old.
07-10-2019, 12:27 PM
#36
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Join Date: 04-08-2008
Location: Lacombe, LA
Posts: 131
This is interesting.
I get a code U0073 or U0100 when it is hot out and the windows are closed in the car. This is a random thing.
When I get in I have to open the windows that's how hot it can feel inside.
I haven't measured the values of the Can bus at the ODB port when this happens because of the pain to disconnect the battery.
When you originally tested the two wires at the port did you see a resistance value different than when the battery was not disconnected ?
I get a code U0073 or U0100 when it is hot out and the windows are closed in the car. This is a random thing.
When I get in I have to open the windows that's how hot it can feel inside.
I haven't measured the values of the Can bus at the ODB port when this happens because of the pain to disconnect the battery.
When you originally tested the two wires at the port did you see a resistance value different than when the battery was not disconnected ?
07-10-2019, 01:14 PM
#37
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Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 24,693
This explains the observed voltages. The actual readable voltage on the wires is not important since it is a digital circuit. The voltage is constantly changing so fast that you can't observe it.
From https://en.wikipedia.org/wiki/CAN_bus (guaranteed to make your eyes glaze over)
From https://en.wikipedia.org/wiki/CAN_bus (guaranteed to make your eyes glaze over)
High speed CAN signaling drives the CAN high wire towards 5 V and the CAN low wire towards 0 V when transmitting a dominant (0), and does not drive either wire when transmitting a recessive (1). Designating "0" as dominant gives the nodes with the lower ID numbers priority on the bus. The dominant differential voltage is a nominal 2 V. The termination resistor passively returns the two wires to a nominal differential voltage of 0 V. The dominant common mode voltage must be within 1.5 to 3.5 V of common and the recessive common mode voltage must be within +/-12 of common.
07-12-2019, 07:53 AM
#38
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Join Date: 04-08-2008
Location: Lacombe, LA
Posts: 131
About 35 miles accumulated since I cleaned the front wheel speed sensors and no issues. Drove the car for 16 miles last night with a scanner monitoring OBD2 and ABS functions. All wheel sensors in sync and no abnormal operating conditions. I will do a 40 mile test this weekend after the storm passes..