Test DJ: Air Conditioning Evaporator Temperature Sensor: Testing

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 2002 Lincoln Town Car, 2002 Lincoln Navigator, 2002 Lincoln LS, 2002 Lincoln Continental, and 2002 Lincoln Blackwood. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

NOTE: If a scan tool communication concern exists, remove jumper wire and go to step 4).

1) KOEO & KOER DTC P1437: Simulate Opposite Signal To PCM
DTC P1437 is set when ACET signal is more than self-test maximum of 4.5 volts. Possible causes for this fault are:
- ACET Circuit Open Or Shorted To VREF
- SIG RTN Circuit Open To ACET Sensor
- Faulty ACET Sensor
- Faulty Powertrain Control Module (PCM)
Disconnect ACET sensor connector. Connect a jumper wire between ACET and SIG RTN circuits at ACET sensor harness connector. Repeat KOEO or KOER self-test where DTC P1437 was received.

If DTC P1436 is received during self-test, replace ACET sensor. If DTC P1436 is not received during self-test, turn ignition switch to OFF position, remove jumper wire and go to next step.

2) Check ACET & SIG RTN Circuits For Open In Harness

Disconnect PCM connector(s). Using a DVOM, measure resistance of ACET and SIG RTN circuits between PCM harness connector and ACET sensor harness connector. If both resistance measurements are less than 5 ohms, replace PCM. If either resistance measurement is 5 ohms or more, repair open in affected circuit.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 4). No test procedures have been omitted.

4) Check ACET Circuit For Short To VREF In Harness

Turn ignition switch to OFF position. Disconnect PCM connector(s). Using a DVOM, measure resistance between ACET and VREF circuits at PCM harness connector. If resistance measurement is more than 10 k/ohms, replace PCM. If resistance is 10 k/ohms or less, repair short between ACET and VREF circuits.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

5) KOEO & KOER DTC P1436: Simulate Opposite Signal To PCM
DTC P1436 is set when ACET signal is less than self-test minimum of .13 volt. Possible causes for this fault are:
- ACET Circuit Shorted To GND Or SIG RTN
- Faulty ACET Sensor
- Faulty Powertrain Control Module (PCM)
Disconnect ACET sensor connector. Repeat KOEO or KOER self-test where DTC P1436 was received. If DTC P1437 is received, replace ACET sensor. If DTC P1437 is not received, go to next step.

6) Check ACET Circuit For Short To Ground In Harness

Disconnect PCM connector(s). Using a DVOM, measure resistance between ACET and SIG RTN circuits at ACET sensor harness connector. Also, measure resistance between ACET circuit at ACET sensor harness connector and ground. If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short in affected circuit.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

NOTE: For DTC P1436, a sudden change could indicate a short to GND. For DTC P1437, a sudden change could indicate an open ACET or SIG RTN circuit.

10) Continuous Memory DTC P1436 OR P1437: Check ACET & SIG RTN Circuits For Intermittent Concerns
Disconnect ACET sensor connector. Using a DVOM, measure voltage between ACET and SIG RTN circuits at ACET sensor harness connector. Turn ignition switch to ON position. While monitoring voltage reading on DVOM, shake, wiggle and bend small sections of wiring harness while working toward PCM. Voltage should be a constant 4.5-5.5 volts. Voltage reading will change suddenly when a fault is detected.
Turn ignition switch to OFF position. Inspect associated connectors for damage. If there is any change in voltage reading, or if a concern is found, isolate fault and repair as necessary. If no faults are indicated, concern is intermittent and cannot be identified at this time. Go to TEST Z, step 1) .