Diagnostic Aids

Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following:

Wiring Harness Circuits (MAP SIG, SIG RTN & VREF)
Faulty TMAP Sensor
Faulty Powertrain Control Module (PCM)

1) DTC P0107, P0108 Or P0109: Check MAP PID

These DTCs indicate intermittent TMAP sensor failure or TMAP sensor reference voltage fell below calibrated limit of .25 volt or exceeded calibrated limit of 5 volts. Possible causes for these faults are:

VREF Circuit Open, Shorted to Ground Or VPWR
TMAP Signal Shorted To VPWR
Faulty TMAP Sensor
Faulty PCM

NOTE: If local barometric pressure is not corrected to sea level or cannot be obtained, check a known good vehicle MAP sensor output to determine actual barometric pressure.

Obtain barometric pressure measurement for location, day and altitude of area. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select MAP PID from PID/DATA MONITOR & RECORD menu. Compare MAP PID value to specifications in TMAP SENSOR DATA table. If MAP PID value is within specification, go to next step. If MAP PID value is not within specification and DTC P0108 was retrieved, go to step 7), for all others go to step 4).

TMAP SENSOR DATA

Barometric Pressure - In. Hg (kPa)	Volts
3.0 (10.0)	.5
6.8 (23.1)	1.0
10.7 (36.1)	1.5
18.5 (62.3)	2.5
20.4 (68.8)	2.7
22.3 (75.4)	3.0
26.2 (88.4)	3.5
27.2 (91.7)	3.6
28.1 (95.0)	3.75
29.1 (98.2)	3.8
30.1 (101.5)	4.0
31.1 (104.8)	4.12
32.0 (108)	4.25

2) Check TMAP Transition

Turn ignition switch to OFF position. Remove TMAP from intake manifold. Turn ignition switch to ON position. Using scan tool, select MAP PID from PID/DATA MONITOR & RECORD menu. Connect vacuum pump to TMAP sensor. Monitor MAP PID while slowly applying 18 in. Hg of vacuum to TMAP sensor. If MAP PID value decreases smoothly when vacuum is applied, go to next step. If MAP PID value does not decrease smoothly when vacuum is applied, replace TMAP sensor.

3) Check TMAP Output With Vacuum Applied

Subtract applied vacuum from local barometric pressure. Use the following equation for MAP PID value:
1. Subtract 18 in. Hg (applied vacuum) from 28.7 in. Hg (local barometric pressure) = 10.7 in. Hg. Voltage should be about 1.5 volt. Refer to TMAP SENSOR DATA table.
Compare MAP PID value with voltage specification in TMAP SENSOR DATA table. If MAP PID value is within specification, fault cannot be duplicated at this time. go to TEST Z, step 1) . If MAP PID value is not within specification, replace TMAP sensor.

4) Check VREF Voltage To TMAP Sensor

Disconnect TMAP sensor connector. Using a DVOM, measure voltage between TMAP harness connector SIG RTN and VREF terminals. See Fig 1. If voltage measurement is 4-6 volts, go to next step. If voltage measurement is not 4-6 volts, go to TEST C, step 1).

Fig 1: Identifying TMAP Sensor Harness Connector Terminals (Ranger 2.3L 4V)
Courtesy of FORD MOTOR CO.

5) Check MAP Circuit For Short To PWR

Using a DVOM, measure voltage between TMAP harness connector MAP and SIG RTN terminals. See Fig 1. If voltage measurement is less than 5 volts, go to next step. If voltage measurement is 5 volts or more, go to step 7).

6) Check MAP Signal Circuit

Turn ignition switch to OFF position. Disconnect TMAP sensor connector. Connect a jumper wire between TMAP harness connector MAP and VREF terminals. See Fig 1. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select MAP PID from PID/DATA MONITOR & RECORD menu. If scan tool communication problem is present, disconnect jumper wire and go to step 8). If MAP PID shows VREF, replace TMAP sensor. If MAP PID does not show VREF, go to step 9).

7) Isolate Source Of Short To PWR In MAP Circuit

Turn ignition switch to OFF position. Disconnect PCM connector(s). Turn ignition switch to ON position. Using a DVOM, measure voltage between TMAP harness connector MAP and SIG RTN terminals. See Fig 1. If voltage is more than one volt, repair short to PWR in affected circuit. If voltage is one volt or less, replace PCM.

8) Check For Shorted MAP Circuit

Turn ignition switch to OFF position. Disconnect scan tool from DLC. Disconnect PCM connector(s). Using a DVOM, measure resistance between PCM harness connector MAP terminal, and SIG RTN and PWR GND terminals. See PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION table. See Figure or Figure . If each resistance measurement is more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short in affected circuit.

9) Check MAP Circuit For Open

Turn ignition switch to OFF position. Disconnect PCM connector(s). Using a DVOM, measure resistance of MAP circuit between PCM harness connector terminal and TMAP sensor harness connector terminal. See Fig 1. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open in MAP circuit.