SAAB WIS ONLINE

(771-2720) TPMS warning tell-tale

TECHNICAL SERVICE BULLETIN
Bulletin Nbr: 771-2720
Date: ........... December 2008
Market: US/CA
TPMS warning tell-tale

Cars affected

Saab 9-3 och 9-5 M08-09.

Background

This bulletin is made to explain the difference between "Check Tire Pressure" / "Low Tire Pressure" and "Service Tire Pressure Monitor System" messages.



Procedure

When a customer complains on a condition related to tire pressure monitoring, it is very important to distinguish between "Check Tire Pressure" / "Low Tire Pressure" conditions and "Service Tire Pressure Monitor System" messages. Understanding the difference between the distinct conditions will help you to distinguish between normal system operation (tire needs air) and a system malfunction.

There is one tell-tale in MIU to indicate both conditions which can be determined by an ignition cycle. A message in SID will also tell the customer what to do.


If the tell-tale light is steady on after an ignition cycle the customer needs to re-inflate his tire/s. Refer to section 1 - Check Tire Pressure / Low Tire Pressure below.

If the tell-tale light after an ignition cycle is flashing for 60 seconds and then remains on it is most probably a system failure. Refer to section 2 - System error messages.

The warranty issues are described in section 4 - Warranty.



1. Check Tire Pressure / Low Tire Pressure

Warning tell-tale in Main Instrument Unit (MIU)

During a "Check Tire Pressure" / "Low Tire Pressure" condition the tell-tale will stay on solid and no failure codes are set.


Check Tire Pressure Warning

Occurs when the tire pressure has decreased to a warning level which is depending on the tire loading information label value.

Tire loading information label value Warning level
psi kPa psi kPa
32 220 25 180
35 240 27 196
36 250 29 204



Low Tire Pressure Alarm

Occurs when the tire pressure has decreased to 24 psi (165 kPa) independent of the tire loading information label value. An alarm message is also received when leakage is greater than 3 psi/min (21 kPa/min).


Procedure

The TPM system is operating as designed.


The customer needs to correct the tire pressure. Use a good quality pocket-type gauge to check tire pressure. One cannot tell if the tires are properly inflated simply by looking at them. Show the customer where to find the information in the owner's manual and on the label as well.

Inform the customer about the effects of outside temperature on tire pressures, refer to section 3 - The Effect of Outside Temperatures on Tire Pressures. Tire pressure increases as the tires become warm (e.g. 4 psi (28 kPa)). Never reduce the pressure of a hot tire. If the tires are hot when you check them, only increase the pressure, if necessary.


2. System error messages


Warning tell-tale in Main Instrument Unit (MIU)

During a "Service Tire Pressure Monitor System" condition the tell-tale will initially flash for 60 seconds and then turn solid after an ignition cycle. Failure codes WILL be set.

System error message


TPMS has set failure codes or does not communicate on the bus.

Procedure

Connect the diagnostic tool, TECH2, to read out the failure codes and follow the procedure in WIS.

Note
- Saab uses an Auto-learn and Auto-locate system and the only allowed diagnostic tool is the TECH2.

- Kent-Moore special tool # J-46079 that is used on other GM brand shall NOT be used on Saab 9-3/9-5 vehicles.


3. The Effect of Outside Temperatures on Tire Pressures

Important: As a rule of thumb, tire pressure will change about 7 kPa (1 psi) for every 6ºC (approx. 15ºF) decrease in temperature - dropping when it gets colder outside, rising when it gets warmer.

Tire pressure should be set to the specified tire loading information label pressure at the lowest seasonal temperature the vehicle will encounter during operation.

The correct action to avoid "Check Tire Pressure" messages due to extreme temperature changes is to do the following:


Use an accurate, high quality tire pressure gauge.

Adjust the tire pressure to the tire loading information label values after every tire rotation.

Let the vehicle sit and adjust the tire pressure to the specified value when the tire temperature is at the lowest expected temperature.

Never set the tire pressure below the tire loading information label value regardless of tire temperature or ambient temperatur.


Important: On extremely cold days, if setting the tire pressure when the vehicle has been indoors, it may be necessary to compensate for the low outside temperatur by adding 21-28 kPa (3-4 psi) more than the tire loading information label pressure. At some later time, when the tires are cold (outdoors), the pressure should be re-checked and adjusted to the tire loading information label pressure if necessary.

4. Warranty Information


1. If a customer complains on a "Check Tire Pressure" / "Low Tire Pressure" message and tell-tale on (tell-tale was on steady - no flashing), the tires should simply be inflated to the proper pressure - this is not a warrantable repair. Also show the customer where to find the information in the owner's manual and on the label.

2. When customers bring their vehicle into the dealership with a Service Tire Pressure Monitor System message and tell-tale (flashes on startup and TECH2 codes in system) use Published Labor Operation Time in STM. However, if a sensor is missing on any tire - this is not a warrantable repair.