NO.27 CONSTANT VOLTAGE [AJ (3.0L Duratec)]

27	Constant voltage
DESCRIPTION	• Incorrect constant voltage
POSSIBLE CAUSE	• Constant voltage circuit malfunction Note • TP sensor and EGR boost sensor use constant voltage.


STEP	INSPECTION	RESULTS	ACTION
1	• Disconnect appropriate sensor connector when constant voltage circuit inspection failed. • Turn key to ON (Engine OFF). • Measure voltage between following appropriate sensor connector terminals: - Constant voltage terminal and GND terminal • Is constant voltage above 6.0 V?	Yes	Go to Step 13.
1		No	Go to the next step.
2	• Is voltage across battery terminals above 10.5 V?	Yes	Go to the next step.
2	• Is voltage across battery terminals above 10.5 V?	No	Inspect charging system.
3	• Turn key to OFF. • Leave appropriate sensor connector disconnected. • Measure voltage between battery positive terminal and GND (between PCM and appropriate sensor) circuit at appropriate sensor connector. • Is voltage above 10.5 V and within 1.0 V of battery voltage?	Yes	Go to the next step.
3		No	Go to Step 8.
4	Note • Purpose of this step is to determine if WDS or equivalent is communicating with PCM. • Turn key to ON (Engine OFF). • Attempt to access ECT PID. • Can ECT PID be accessed?	Yes	Go to Step 7.
4		No	Go to the next step.
5	• Turn key to OFF. • Disconnect TP sensor, EGR boost sensor and PCM connectors. • Turn key to ON (Engine OFF). • Measure voltage between following PCM connector terminals. - 71/97 and 24/51/76/103 (R.H.D.) - $C-36/C-35 and C-47/C-48/C-49 (L.H.D.) • Is voltage above 10.5 V?	Yes	Go to the next step.
5		No	Repair open circuit between PCM terminal 71 and/or 97 (R.H.D.)/C-35 and/or C-36 (L.H.D.) and main relay.
6	• Leave TP sensor, EGR boost sensor and PCM connectors disconnected. • Measure resistance between PCM connector terminals. - 90 and 24/51/76/103 (R.H.D.) - $E-40 and C-47/C-48/C-49 (L.H.D.) • Is resistance above 10 kilohms?	Yes	Inspect for constant voltage at suspect sensor connector again.
6		No	Repair constant voltage circuit shorted to GND.
7	• Turn ignition switch off. • Leave TP sensor disconnected. • Disconnect PCM connector. • Measure resistance between PCM connector terminal 90 and constant voltage circuit at appropriate sensor connector. • Is resistance below 5.0 ohms?	Yes	Inspect for constant voltage at suspect sensor connector again.
7		No	Repair open constant voltage circuit.
8	Note • Purpose of this step is to determine if WDS or equivalent is communicating with PCM. • Reconnect TP sensor connector. • Turn ignition switch on. • Attempt to access ECT PID. • Can ECT PID be accessed?	Yes	Go to the next step.
8		No	Go to Step 11.
9	• Are DTCs present for two or more sensors connected to PCM terminal 91? • Sensor connected to PCM terminal 91: - ECT sensor (P0117, P0118, P0125) - BARO sensor (P0107, P0108) (European (L.H.D.) specs.) - EGR boost sensor (P0106, P0107, P0108) (Australian, General (L.H.D. R.H.D.) specs.) - HO2S (front) (P0131, P0132, P0134, P0151, P0152, P0154) - HO2S (rear) (P0138, P0140, P0158, P0160) - IAT sensor (P0111, P0112, P0113) - TP sensor (P0121, P0122, P0123)	Yes	Go to the next step.
9		No	Repair open GND circuit to sensor where constant voltage circuit inspection failed.
10	• Turn key to OFF. • Disconnect WDS or equivalent from DLC-2. • Disconnect PCM connector. • Measure resistance between GND circuit at appropriate sensor connector and PCM connector terminal 91. • Is resistance below 5.0 ohms?	Yes	Reconnect sensor connector. Go to appropriate DTC test.
10		No	Repair open GND circuit.
11	• Turn key to OFF. • Disconnect PCM connector. • Measure resistance between battery negative terminal and following PCM terminals. - 3/24/51/76/103 (R.H.D.) - $C-47/C-48/C-49 (L.H.D.) • Is each resistance below 5.0 ohms?	Yes	Go to the next step.
11		No	Repair open GND circuit.
12	• Turn key to OFF. • Measure resistance between GND circuit at following sensor connector and GND: - TP sensor - EGR boost sensor - ECT sensor - IAT sensor - HO2S (front) - HO2S (rear) • Is each resistance below 5.0 ohms?	Yes	GND circuits are okay. Inspect for constant voltage at suspect sensor connector again.
12		No	Inspect for open GND circuit.
13	• Turn key to OFF. • Disconnect TP sensor, EGR boost sensor, and PCM connectors. • Turn key to ON (Engine OFF). • Measure voltage between constant voltage circuit at TP sensor connector and battery negative terminal. • Is voltage below 0.5 V?	Yes	Inspect for constant voltage at suspect sensor connector again.
13		No	Repair constant voltage circuit shorted to power in harness.
14	• Verify test results. - If okay, return to diagnostic index to service any additional symptoms. - If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace PCM.