Gearbox fault, P0829 code
#1
07-25-2017, 09:32 PM
Gearbox fault, P0829 code
Hello, posting some details just to record them for others....I've poked around the internet enough to know I don't have great options 
I received the car in August 2014 with 78K miles and the previous owner (my parents, who bought it new) never reported this issue. They drove the car mostly around town with a few early cross country trips. My driving was quite different, twisty mountain roads and frequent highway miles.
Nov 11, 2014:
Dash light came on (Gearbox fault) and car wouldn't shift out of its current gear. Driving was twisty mountain roads, coasting to slow down at the end. Pulled over, turned off and all was well. No engine light, but I took it to the shop and they found P0829 code, gear load fault between 5-6 gear. Indy tech recommended reman. trans $6700. He said he would keep driving until it got worse before fixing. I wasn't high on a re-manufactured transmission that cost the same as the car was worth
Nov 21, 2014:
TCM refresh after finding this ...JTB00072. Dealer wasn't aware of this, but I pushed and it was several months before I got the code again. Checked connections and for leaks at this time.
I have been getting the gearbox fault every now and then since 2014. Almost always on freeways when traffic sneaks up and I let off the gas to slow down (no braking). Shutting off engine has always cleared the gearbox fault. It hasn't gotten better or worse.
July 21, 2017:
Usual gearbox fault on freeway, pulled over and turned off car. Resumed with no errors. But it happened twice and the second time, engine light stayed on (because of consecutive faults). This is the first time it happened twice in one trip and triggered the check engine light. I have a reader, confirmed P0829 and cleared the code myself.
I have done the 100K service already (car has 98K miles, just for background). Regular Jaguar maintenance done (meaning water pump, ignition coils, thermostat, new lug nuts, etc. )
I received the car in August 2014 with 78K miles and the previous owner (my parents, who bought it new) never reported this issue. They drove the car mostly around town with a few early cross country trips. My driving was quite different, twisty mountain roads and frequent highway miles.
Nov 11, 2014:
Dash light came on (Gearbox fault) and car wouldn't shift out of its current gear. Driving was twisty mountain roads, coasting to slow down at the end. Pulled over, turned off and all was well. No engine light, but I took it to the shop and they found P0829 code, gear load fault between 5-6 gear. Indy tech recommended reman. trans $6700. He said he would keep driving until it got worse before fixing. I wasn't high on a re-manufactured transmission that cost the same as the car was worth
Nov 21, 2014:
TCM refresh after finding this ...JTB00072. Dealer wasn't aware of this, but I pushed and it was several months before I got the code again. Checked connections and for leaks at this time.
I have been getting the gearbox fault every now and then since 2014. Almost always on freeways when traffic sneaks up and I let off the gas to slow down (no braking). Shutting off engine has always cleared the gearbox fault. It hasn't gotten better or worse.
July 21, 2017:
Usual gearbox fault on freeway, pulled over and turned off car. Resumed with no errors. But it happened twice and the second time, engine light stayed on (because of consecutive faults). This is the first time it happened twice in one trip and triggered the check engine light. I have a reader, confirmed P0829 and cleared the code myself.
I have done the 100K service already (car has 98K miles, just for background). Regular Jaguar maintenance done (meaning water pump, ignition coils, thermostat, new lug nuts, etc.
)
#2
07-26-2017, 05:52 PM
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I have no direct experience of gearbox faults (thank goodness) but I have learnt a few things
on this forum and my own research.
The mechatronic is removable from the gearbox and the gear changes are controlled by solenoids
which can fail or suffer supply or earth faults.
5-6 shift solenoid failure
Electrical short to power
- pinched wires Electrical short to ground
- pinched wires Open in power or ground circuit wiring
- disconnected or loose connections TCM or PCM internal failure
Possible Solutions
Disconnect PCM or TCM wiring harness, depending on the application and using an electrical diagram as reference, check for excessive resistance or an open in the control circuit.
Using a Digital Volt Ohm Meter (DVOM) set to the Ohms scale, check for resistance on the 5-6 solenoid power and ground sources to determine if there is an open circuit or excessive resistance in the 5-6 solenoid.
Visually inspect for for any pinched, disconnected or loose wires on the harness connectors.
Short to power: Disconnect battery positive cable and wiring harness connector at transmission and check for continuity using the
DVOM between power source and solenoid circuit wiring in key on / engine off (KOEO) position as well as the key off position.
Read more at: https://www.obd-codes.com/p0829
Copyright OBD-Codes.com
The most probable root cause is a solenoid failure hence if you don't do it yourself you need a transmission specialist
who is prepared to test and replace a solenoid and doesn't want to flog you another gearbox.
on this forum and my own research.
The mechatronic is removable from the gearbox and the gear changes are controlled by solenoids
which can fail or suffer supply or earth faults.
5-6 shift solenoid failure
Electrical short to power
- pinched wires Electrical short to ground
- pinched wires Open in power or ground circuit wiring
- disconnected or loose connections TCM or PCM internal failure
Possible Solutions
Disconnect PCM or TCM wiring harness, depending on the application and using an electrical diagram as reference, check for excessive resistance or an open in the control circuit.
Using a Digital Volt Ohm Meter (DVOM) set to the Ohms scale, check for resistance on the 5-6 solenoid power and ground sources to determine if there is an open circuit or excessive resistance in the 5-6 solenoid.
Visually inspect for for any pinched, disconnected or loose wires on the harness connectors.
Short to power: Disconnect battery positive cable and wiring harness connector at transmission and check for continuity using the
DVOM between power source and solenoid circuit wiring in key on / engine off (KOEO) position as well as the key off position.
Read more at: https://www.obd-codes.com/p0829
Copyright OBD-Codes.com
The most probable root cause is a solenoid failure hence if you don't do it yourself you need a transmission specialist
who is prepared to test and replace a solenoid and doesn't want to flog you another gearbox.
Last edited by meirion1; 07-26-2017 at 05:55 PM.