Test Kl: Manifold Intake Air Heater: Testing

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2002 Ford RV Cutaway, 2002 Ford Pickup, 2002 Ford F550 Super Duty, 2002 Ford F450 Super Duty, and 2002 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

1) KOEO, KOER & Continuous Memory DTC P0640: Check Power Feed To Relay Coil
DTC P0640 indicates MIAH relay coil circuit fault. Possible causes are:
- Open VPWR Circuit To MIAH Relay
- Open MIAH Control Circuit To MIAH Relay
- Faulty MIAH Relay
- Faulty PCM
Turn ignition on. Using DVOM, measure voltage between chassis ground and MIAH relay VPWR terminal (Red wire). See Figure. MIAH relay is located on top of engine. See Figure. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in Red wire between MIAH relay and central junction box. Clear DTCs and retest.

2) Isolate Relay

Turn ignition off. Disconnect MIAH control circuit (Violet wire) from MIAH relay terminal. Connect a jumper wire between chassis ground and MIAH control circuit terminal at MIAH relay. Cycle ignition on, then off and listen for an audible "click" from MIAH relay. If relay "clicks", go to next step. If relay did not "click", replace MIAH relay. Clear DTCs and retest.

3) Isolate PCM

Disconnect PCM connector and inspect connector for damaged pins, corrosion and loose wires. PCM is located in left rear of engine compartment, near brake master cylinder. Repair connector as necessary. Using DVOM, measure resistance of Violet wire between MIAH relay control circuit and test pin No. 98 at breakout box. If resistance is less than 5 ohms, replace PCM. Clear DTCs and retest. If resistance is 5 ohms or more, repair open in Violet wire between PCM and MIAH relay. Clear DTCs and retest.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

4) KOER & Continuous Memory DTC P0541 & P0542: Check B+ Circuit To MIAH Relay
DTC P0541 indicates MIAH monitor circuit low fault. DTC P0542 indicates MIAH monitor circuit high fault. Possible causes are:
- B+ Circuit To MIAH Relay Open
- MIAH Monitor Circuit Open
- Faulty MIAH Relay
- Faulty PCM
Turn ignition on. Using DVOM, measure voltage between chassis ground and B+ circuit terminal (Black/Orange wire) at MIAH relay. See Figure. MIAH relay is located on top of engine. See Figure. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in Black/Orange wire between MIAH relay and battery fusible links. Clear DTCs and retest.

5) Isolate Relay Contacts

Turn ignition off. Connect jumper wire between MIAHM circuit (Red/Yellow wire) and B+ (Black/Orange wire) circuit at MIAH relay terminals. Clear DTCs and repeat QUICK TEST . If DTC is still present, go to next step. If DTC is no longer present, replace MIAH relay. Clear DTCs and retest.

6) Check MIAH Monitor Circuit For Open

Disconnect PCM connector and inspect for damaged pins, corrosion and loose wires. PCM is located in left rear of engine compartment, near brake master cylinder. Repair connector as necessary. Install Rotunda Breakout Box (014-00950), leaving PCM disconnected. Using DVOM, measure resistance of MIAHM circuit (Red/Yellow wire) between test pin No. 3 at breakout box and MIAH relay. If resistance is less than 5 ohms, replace PCM. Clear DTCs and retest. If resistance is 5 ohms or more, repair open in Red/Yellow wire between PCM and MIAH relay. Clear DTCs and retest.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

7) KOEO DTC P0542: Isolate Relay
DTC P0542 indicates MIAH monitor circuit high fault. Possible causes are:
- MIAH Circuit Shorted To Ground
- MIAHM Circuit Shorted To PWR
- Faulty MIAH Relay
- Faulty PCM
Turn ignition off. Disconnect MIAHM circuit (Red/Yellow wire) from MIAH relay terminal. MIAH relay is located on top of engine. See Figure. Turn ignition on. Using DVOM, measure voltage between chassis ground and MIAHM circuit terminal No. 87 at MIAH relay. See Figure. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, leave MIAHM circuit disconnected and go to step 10).

8) Check MIAH Relay Control Circuit

Turn ignition off. Disconnect MIAH control circuit (Violet wire) from MIAH relay terminal No. 86. Using DVOM, measure resistance between chassis ground and MIAH circuit (Violet wire) at relay harness. If resistance is 10 k/ohms or less, go to next step. If resistance is more than 10 k/ohms, MIAH relay contacts are stuck closed. Replace MIAH relay. Clear DTCs and retest.

9) Check PCM Control Circuit

Ensure ignition is off. Disconnect PCM connector and inspect for damaged pins, corrosion and loose wires. PCM is located in left rear of engine compartment, near brake master cylinder. Repair connector as necessary. Using DVOM, measure resistance between chassis ground and MIAH circuit (Violet wire) at relay harness. If resistance is 10 k/ohms or less, repair short to ground in Violet wire between MIAH relay. If resistance is more than 10 k/ohms, check for short to ground at terminal No. 92 at PCM connector. Repair as necessary. If no short to ground is found, replace PCM. Clear DTCs and retest.

10) Check MIAH Monitor Circuit For Short To PWR

Turn ignition off. Disconnect PCM connector and inspect for damaged pins, corrosion and loose wires. PCM is located in left rear of engine compartment, near brake master cylinder. Repair connector as necessary. Install Rotunda Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Using DVOM, measure voltage between chassis ground and test pin No. 3 at breakout box. If voltage is more than 10.5 volts, repair short to voltage in Red/Yellow wire between PCM and MIAH relay. Clear DTCs and retest. If voltage is 10.5 volts or less, check for short to voltage at terminal No. 3 at PCM connector. Repair as necessary. If no short to voltage is found, replace PCM. Clear DTCs and retest.