Transmission Failure

[IrvesBMW]

My X5 intermittently displayed "transmission malfunction" on the dashboard for approximately four months. No drivability concerns were present. Suddenly, it failed to crank, start, or activate the accessory lights upon pressing the start button. I scanned it and discovered a trans code indicating a voltage of less than 6.7v. I examined the battery and measured 12.43 volts. I charged the battery nonetheless. I subsequently verified the power flow from the battery to the fuse box and then to the transmission connector. I replaced the starter as planned, and I also replaced the GCS/valve body under the assumption that the transmission computer was defective. Unsuccessful. What should I do next?

[IrvesBMW]

[ByteStorm]

Given the several problems, it appears to be a power supply issue. You are at the wiring diagram section to verify the power supplies from the CAS and JBE, as that is where the power for the various modules in the vehicle originates

[IrvesBMW]

Firstly, I greatly appreciate your response! This situation is overwhelming me! I verified the electricity from the fuse through the firewall connector. From that point to the trans connection plug, power was sent to the GCS. I was attempting to ascertain which pin directed to the subsequent location and what that entailed. I am presently attempting to identify the CAS module to confirm the power and signal to it at this moment.

[CyberNinja]

I consistently advocate for initiating with the utmost simplicity with such matters.

Given the intermittent nature of the issue, which has escalated to a non-drivable problem, have you verified that all ground connections are secure and free from corrosion? There are numerous items in the new BMWs, including some located beneath the front carpeting. If it has been malfunctioning for an extended period, it may have become detached beyond its capacity to ground, or the vehicle may have experienced prior water intrusion, resulting in mild corrosion of the ground connection.


A friend of mine with an X6M recently encountered a comparable problem. He took it to an independent mechanic who replaced numerous components without success. I visited, lifted the front passenger carpet (the passenger side on a left-hand drive UK vehicle, near the A-pillar just south of the glove box), cleaned and secured the three grounding points located beneath it (the bottom two were corroded due to his wife leaving a window open, which soaked the passenger side years prior). After addressing this, I pressed the button, and it started immediately—there have been no issues since.

[CyberNinja]

I consistently advocate for initiating with the utmost simplicity when addressing such challenges.

Given its intermittent nature followed by a non-drivable issue, have you verified that all ground connections are secure and free from corrosion? There are numerous items in the new BMWs, including some located beneath the front carpeting. If it has been malfunctioning for some time, it may have become detached beyond its capacity to ground, or the vehicle may have experienced prior water intrusion, resulting in mild corrosion of the ground connection.


A friend of mine with an X6M recently encountered a comparable issue. He took it to an independent mechanic who replaced numerous components without resolving the problem. I visited, lifted the front passenger carpet (the passenger side on a left-hand drive UK vehicle, near the A-pillar just south of the glove box), cleaned and tightened the three grounding points located there (the bottom two were corroded due to his wife leaving a window open, which soaked the passenger side years prior). After pressing the button, the vehicle started without any subsequent issues.

[CyberNinja]

😁