Diagnostic Trouble Codes (DTCs)

WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

If the control module detects a fault it stores a diagnostic trouble code (DTC) and the orange indicator LEDs in the REC and air conditioning (A/C) buttons flashes for approximately 20 seconds. The control module can store up to 38 diagnostic trouble codes (DTCs). If the total diagnostic trouble code (DTC)s exceeds 10 the five first diagnostic trouble code (DTC)s will always be saved, while the last five become the latest diagnostic trouble code (DTC)s to be stored.

If for some reason a fault disappears after the diagnostic trouble code (DTC) has been permanently stored in the control module, information about the fault is stored in the control module.

Every diagnostic trouble code (DTC) has a counter which records the number of cycles which have been " fault-free" since the diagnostic trouble code (DTC) was stored (intermittent fault). A cycle is defined from when the ignition was switched on, was then on for at least 10 seconds and then switched off. Every time the cycle runs without the control module registering the fault again, increases the counter by 1. Using the counter it is possible to determine if the control module interprets diagnostic trouble code (DTC) as permanent or intermittent. When the counter is at 0 the transmission control module (TCM) treats the malfunction as a permanent fault. If the counter value is greater than 0 the control module interprets this as meaning the fault is intermittent.