When a customer comes in with a Tire Pressure Monitor
(TPM) condition, the proper strategy is to determine the nature of the low tire
pressure light -- whether it is related to low air pressure or a system fault.
Solid Light
- If the low tire pressure light is on constantly, the TPM system is working
properly. The owner needs to adjust tire pressures properly and drive the
vehicle to turn off the light.
Flashing Light - If the low tire pressure light flashes for a minute, and then stays
on, a TPM system problem exists and a DTC will have set.
Solid Light On, Then Off - If the low tire pressure light comes on initially,
but goes off after driving awhile, the system is working properly. Pressure in
one or more tires is low enough to turn the light on when cold but increases
when the tire warms up, causing the light to turn off. The system is working
properly. Adjust tire pressures properly to turn off the light.
TPM Relearn
When performing a TPM relearn (only after a tire
rotation or replacement of a TPM sensor or module), always use a scan tool to
initiate the relearn process. A scan tool-initiated relearn locks out other
vehicle TPM signals that may be broadcasting in the area. This method avoids
storing false TPM IDs and will prevent the system from flashing the tire
pressure monitor light or displaying dashes (---) in tire pressure readouts.
Checking the four TPM IDs with the scan tool before and following relearn to
verify they are the same can prevent invalid ID learns.
- Thanks to Ray Romeo
Leave a comment