Tire Pressure Monitoring - 2012 Jeep Wrangler JK Factory Service Manual

BASE TIRE PRESSURE MONITORING

This system will consist of Tire Pressure Monitoring (TPM) sensors attached to each wheel through the valve stem mounting hole, a Wireless Control Module (WCM) and a yellow TPM telltale lamp. A TPM sensor shall be installed in the spare wheel if the vehicle is equipped with a matching full size spare wheel and tire assembly.

NOTE:
The Tire Pressure Monitoring System (TPMS) will warn the driver of a low tire pressure based on the vehicle recommended cold placard pressure.

The tire pressure will vary with temperature by about 1 psi (6.9 kPa) for every 12°F (6.5°C). When the outside temperature decreases, the tire pressure will decrease. Tire pressure should always be set based on cold inflation tire pressure. This is defined as the tire pressure after a vehicle has not been driven for more than 3 hours - and in outside ambient temperature. The tire pressure will also increase as the vehicle is driven - this is normal and there should be no adjustment for this increased pressure.

The TPM System will warn the driver of a low tire pressure if the tire pressure falls below the low pressure warning threshold for any reason, including low temperature effects.

The TPM System will continue to warn the driver of low tire pressure as long as the condition exists, and will not turn off until the tire pressure is at or above recommended cold placard pressure. Once the low tire pressure warning has been illuminated, the tire pressure must be increased to the recommended cold placard pressure in order for the TPM warning lamp to be turned off. The system will automatically update and the TPM warning lamp will extinguish once the updated tire pressures have been received. The vehicle may need to be driven for up to 10 minutes above 15 mph (25 kph) to receive this information.

WIRELESS CONTROL MODULE (WCM)

The receiver circuit for the TPM system is integrated into the WCM. for non-remote start vehicles. For factory installed remote start vehicles, the remote start antenna is external to the WCM. The WCM can also include the Remote Keyless Entry (RKE) receiver, Remote Start (if equipped), and the Sentry Key Immobilizer (SKIM) receiver. All Four receivers share a number of common components. The WCM decodes the RF signals transmitted by each of the vehicle's tire pressure sensors. The decoded information is used to determine if "warning" or "fault" conditions exist within the TPM system.

The WCM communicates with the module that controls the "TPM telltale lamp", via the vehicle bus system.

Upon detection of a warning or fault condition, the WCM will send a request to illuminate or flash the yellow TPM telltale. Also, upon detection of a warning or fault condition, the display module will send a request to sound the "chime". A chime will only be requested once per ignition cycle per warning or fault condition detected.

The WCM will store all warning and fault conditions, placard pressure values, low-pressure threshold values and low pressure threshold hysteresis values in memory that can be accessed through diagnostic communication. If new sensors are introduced to the vehicle, the data stored for the sensor being replaced will be deleted.

The WCM will store all wheel sensor ID's and locations and faults in memory that can be accessed through diagnostic communication. All other data values transmitted from each active wheel sensor (not the spare tire) shall be stored in the WCM memory.

The WCM automatically learns and stores the sensor's ID while driving “within 10 minutes continuously above 15 m.p.h. (24 Km/h)” after a sensor has been replaced.

The learning sequence will initiate when the vehicle has been stopped for more then 20 minutes. A new TPM sensor ID can also be programmed directly into the WCM by using a RKE-TPM Analyzer in conjunction with a Scan Tool. Once the new TPM sensor ID has been programmed, the RKE-TPM Analyzer can be used to update the TPMS by activating the TPM sensor.

OPERATION

The tire pressure monitoring system is designed to operate without loss of function for all OEM tire construction for this vehicle. Tire Pressure Monitoring Sensors, mounted to each road wheel as part of the valve stem, transmit an RF signal indicating their individual pressure to a receiver located in the Wireless Control Module (WCM), commonly referred to as the Sentry Key Remote Entry Module (SKREEM).These transmissions occur approximately once every minute at speeds over 15 mph (24 km/h). If the TPM system detects that the tire pressure in any road tire is going low, beyond the Low Pressure (lamp) ON threshold (see placard table below), the TPM system will continuously illuminate an indicator lamp. If a system fault is detected, the indicator lamp will flash on/off for 75 seconds and then remain on solid.

If the WCM detects a warning or fault condition at ignition key "on" it will wait ten seconds +/- 10 % before sending the first request to illuminate the yellow TPM telltale lamp. This will assure that the display module has concluded its bulb check period. The display module will request a chime once per ignition cycle for each "warning" or "fault" condition detected. A "warning" or "fault" condition will remain enabled until the problem causing the condition is corrected and removed/reset.

The WCM shall continuously monitor for the receipt of tire pressure RF message transmissions from the TPM sensors during both the ignition key "on" and key "off" cycles. The TPM sensor ID's and the location of each sensor (e.g. Tire 1, Tire 2 etc.) are stored in the WCM non-volatile memory during the initial Manufacturing Plant Process, or during a service procedure, as required. The recommended "placard pressure", "low-pressure threshold" and “Hysteresis Pressure Values” for the tires installed on the vehicle, are stored in the WCM non-volatile memory during the initial Manufacturing Plant Process, or during a service procedure, as required.

The recommended "Placard Pressure", "Low-pressure Threshold", and "Hysteresis Pressure Values" for the tires installed on the vehicle, are stored in the non-volatile memory during the initial Manufacturing Plant Process, or during a service procedure, as required. To determine the pressure thresholds for a vehicle, refer to the Tire Inflation Pressure (Placard) Label, and then apply the placard pressure to the following table. The Low Pressure Off Threshold is defined as the Low Pressure On Threshold plus the Hysteresis Pressure Value.

TPM THRESHOLD PRESSURES

NOTE:
To determine the pressure thresholds for a vehicle, refer to the Tire Inflation Pressure (Placard) Label found on the Driver's B-Pillar, then apply the placard pressure to the following table.

Placard Pressure (Cold) (PSI)	Low Pressure ON Threshold (PSI)	Low Pressure OFF Threshold (PSI)
28	22	26
29	23	27
30	24	28
31	25	29
32	25	29
33	26	30
34	27	31
35	28	32
36	29	33
37	29	34
38	30	35
39	31	36
40	32	37
41	33	38
42	34	39
43	35	40
44	36	41
45	36	41
46	37	43
47	38	44
48	38	45
49	39	45
50	40	47
51	41	48
55	44	52
60	48	57
65	52	62
70	56	67
75	60	72
80	64	77

TIRE PRESSURE MONITORING SYSTEM

All Tire Pressure Monitoring System Faults are specific to one location. If a "BATTERY LOW" fault is detected it will cause a loss of signal fault. If a "SENSOR FAILURE" fault is detected, the location will be displayed (Premium Systems). The appropriate sensor/transmitter can then be replaced. If a single sensor/transmitter cannot be detected by the WCM, replace that sensor transmitter. If none of the sensors/transmitters can be detected, refer to symptoms in the WCM section. For additional system description and diagnosis, refer to Tire Pressure Monitoring in the Body Diagnostic manual .

TIRE PRESSURE

Check the tire pressure yellow telltale in the instrument cluster. If the yellow telltale is illuminating continuously, adjust the air pressure as necessary to that listed on the Tire Inflation Pressure Label (Placard) provided with the vehicle. After adjusting air pressure in a tire, allow approximately two minutes for the message or yellow telltale to go out. Inspect all the tires for leaks. A water "dunk tank" or other water test may be used as long as any water at the valve core is removed once the procedure is complete. The water can be easily expelled from the core area by pushing in on the core for several seconds, allowing escaping air to drive out any moisture. Reinflate the tire as necessary. Always make sure the original valve stem cap is securely installed to keep moisture out of the sensor. If the yellow telltale is still illuminating continuously or if the yellow telltale is flashing on/off for 60 seconds, once every ten minutes while drive, there is a system fault detected (Refer to 22 - Tires and Wheels/Tire Pressure Monitoring - Diagnosis and Testing) .

SPECIFICATIONS

DESCRIPTION	N·m	Ft. Lbs.	In. Lbs.
Tire Pressure Sensor/Transmitter Mounting Nut	6	—	53

Placard Pressure (Cold) (PSI)	Low Pressure ON Threshold (PSI)	Low Pressure OFF Threshold (PSI)
28	22	26
29	23	27
30	24	28
31	25	29
32	25	29
33	26	30
34	27	31
35	28	32
36	29	33
37	29	34
38	30	35
39	31	36
40	32	37
41	33	38
42	34	39
43	35	40
44	36	41
45	36	41
46	37	43
47	38	44
48	38	45
49	39	45
50	40	47
51	41	48
55	44	52
60	48	57
65	52	62
70	56	67
75	60	72
80	64	77

Placard Pressure (Cold) (PSI)	Low Pressure ON Threshold (PSI)	Low Pressure OFF Threshold (PSI)
28	22	26
29	23	27
30	24	28
31	25	29
32	25	29
33	26	30
34	27	31
35	28	32
36	29	33
37	29	34
38	30	35
39	31	36
40	32	37
41	33	38
42	34	39
43	35	40
44	36	41
45	36	41
46	37	43
47	38	44
48	38	45
49	39	45
50	40	47
51	41	48
55	44	52
60	48	57
65	52	62
70	56	67
75	60	72
80	64	77

Placard Pressure (Cold) (PSI)	Low Pressure ON Threshold (PSI)	Low Pressure OFF Threshold (PSI)
28	22	26
29	23	27
30	24	28
31	25	29
32	25	29
33	26	30
34	27	31
35	28	32
36	29	33
37	29	34
38	30	35
39	31	36
40	32	37
41	33	38
42	34	39
43	35	40
44	36	41
45	36	41
46	37	43
47	38	44
48	38	45
49	39	45
50	40	47
51	41	48
55	44	52
60	48	57
65	52	62
70	56	67
75	60	72
80	64	77