BCM Code F13, In-Vehicle Temperature Sensor: Notes
WARNING: This page is about a different car, the 1992 Cadillac Fleetwood and 1992 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
If this code is not displayed during second pass of diagnostic codes, it is an intermittent failure and cannot be diagnosed using this procedure. Refer to NOTE ON INTERMITTENTS.
In-vehicle temperature sensor uses a thermistor to control signal voltage to BCM. BCM applies and monitors voltage on circuit No. 734 to sensor. When sensor is cold, its resistance is high (BCM will read a high monitored voltage). As sensor warms, its resistance decreases and signal voltage is pulled low through sensor ground circuit No. 736. This signal will vary between 5 volts (open circuit) and zero volts (shorted circuit). Code F13 will set if signal voltage indicates less than -29°F (-34°C) or greater than 205°F (96°C). These conditions can be observed in BCM data display as an in-vehicle temperature reading (parameter P.2.5) outside range.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- If temperature reading changes after disconnecting sensor, BCM and wiring are okay.
- If temperature reading changes after jumpering sensor terminals, BCM and wiring are okay.
- By applying a ground to various points in circuit, an open can be isolated when display changes to outside range of -29°F to 194°F (-34°C to 90°C).