DTC 29

DTC 29 Chart:

Secondary Air Injection Pump Circuit.:

CIRCUIT DESCRIPTION
Ignition voltage is supplied directly to the air pump relay coil on CKT 439. The Powertrain Control Module (PCM) controls the relay by providing the ground path through CKT 436. When the PCM is commanding a component "ON," the voltage of the control circuit should be "low" (near 0 volts). When the PCM is commanding the control circuit to a component "OFF," the voltage potential of the circuit should be "high" (near battery voltage). The primary function of the driver is to supply the ground for the component being controlled.

Each driver has a fault line which is monitored by the PCM. The PCM will monitor the voltage at the driver. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change and the DTC will set.

DTC 29 WILL SET WHEN:
The PCM detects the wrong voltage potential for 26 seconds on CKT 436.

ACTION TAKEN (PCM WILL DEFAULT TO)
The Malfunction Indicator lamp (MIL) will illuminate and the PCM disables the driver for this circuit to prevent internal PCM damage.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test determines if the device can he controlled by the PCM.
2. This check can detect a partially shorted coil which would cause excessive current flow If excessive current flow is detected, a circuit check will he performed to isolate the device from the wiring. leave the circuit energized for 2 minutes to allow the coil to warm up. The coil may open (amps drop to "0") when warm.
3. The remaining circuit checks will identify a circuit problem that has caused an excessive current flow or inoperative relay. If a circuit check is done on a relay, it is important to identity and test the relay coil terminals ("B8" and "C10") to avoid improper diagnosis.

DIAGNOSTIC AIDS
Inspect the harness and all related connectors including the PCM. These may cause an intermittant. Check for damaged or pushed out terminals.