Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTCS 63/64, BARO Sensor Circuit High/Low (4L80-E With TCM): Notes
TCM supplies 5 volts to BARO sensor. As atmospheric pressure changes, resistance within BARO sensor also changes, modifying voltage on BARO sensor input signal. When atmospheric pressure is high (100 kPa) input signal voltage will also be high (about 4.5 volts). As atmospheric pressure decreases, input signal voltage also decreases. DTC 63 will set when:
- BARO sensor signal voltage greater than 4.9 volts.
- Conditions met for more than 2 seconds.
DTC 64 will set when:
- BARO sensor signal voltage less than 1.9 volts.
- Conditions met for more than 2 seconds. TCM will default to no altitude compensation of shift patterns.NOTE: Test numbers refer to numbers on diagnostic chart.
- This verifies 5-volt supply to BARO sensor.
- If entire circuit is okay, voltage measured will be 5 volts.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.