Circuit Description
The Manifold Absolute Pressure (MAP) sensor responds to changes in the intake manifold pressure (vacuum). A 5 volt reference is applied to the sensor on the 5 volt reference circuit. A variable resistor moves in relation to the manifold pressure and a voltage signal is sent back to the VCM on the MAP signal circuit. This voltage signal varies from 1.0-1.5 volts at closed throttle to 4.0-4.5 volts at wide open throttle (low vacuum). The VCM utilizes the MAP signal and throttle position in order to determine the correct amount of fuel delivered to the engine. This DTC is a type A DTC.
Conditions for Setting the DTC
The following conditions will set the DTC:
| • | No TP sensor DTCs are set |
| • | Throttle Position is less than 96.8 when engine speed is less than 1000 RPM |
| • | Or the Throttle Position is no more than 89.8% when engine speed is greater than 1000 RPM |
| • | The MAP is greater than or equal to 4.9 V |
Action Taken When the DTC Sets
The VCM turns ON the MIL when 1 failure has occurred. The VCM substitutes a calculated value for the MAP sensor value so an acceptable driving condition is maintained.
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
Diagnostic Aids
An intermittent ground in the MAP signal or the 5 volt reference circuit results in a DTC P1106.
With the ignition ON and the engine OFF, the manifold pressure is equal to atmospheric pressure with the signal voltage high. The VCM uses this information as an indication of the vehicle's altitude. Comparison of this reading with a known good vehicle using the same sensor is a good way to check accuracy of a suspect sensor. Readings should be the same ±0.4 volts.
Refer to Intermittent Conditions .
Important: The electrical connector must remain securley fastened.
Important: After removing the MAP sensor from the intake manifold, replace the MAP sensor to intake manifold seal.
Remove the MAP sensor. Twist sensor by hand (only) to check for intermittent connections. Output changes greater than 0.1 volt indicates a bad connector or connection. If OK, replace sensor.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Important: Be sure to use the same diagnostic equipment for all measurements.
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This step checks for a short to voltage on the 5V reference circuit.
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This step checks the integrity of the MAP sensor ground circuit.
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The VCM terminals GRY 12 and GRY 27 are spliced together inside the VCM. When checking the 5 volt reference for a short to ground, both the 5 volt reference circuits and all of the components on the 5 volt reference circuits must also be checked.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does the scan tool display a MAP sensor voltage greater than the specified value? | 15 in Hg 4.0 V | ||
3 |
Does the scan tool display a voltage less than the specified value? | 1.0 V | ||
4 | The DTC is intermittent. Are any additional DTCs stored? | -- | Go to The Applicable DTC Tables | Go to Diagnostic Aids |
With a DVM connected to ground, probe the 5 V reference circuit at the MAP sensor harness connector. Is the voltage greater than the specified value? | 5.2 V | |||
6 | Are DTCs P0113, P1106, and P1111 set? | -- | ||
Probe the MAP sensor ground circuit (at the MAP sensor connector) with a test light to B+. Is the test light ON? | -- | |||
8 | Check the MAP sensor vacuum source for a restriction. Was a problem found? | -- | ||
9 | Replace the MAP sensor. Refer to MAP Sensor Replacement for the 4.3L. Is the replacement complete? | -- | -- | |
10 | Check for a short to the voltage in the MAP sensor signal circuit. Was a problem found? | -- | ||
Is the voltage greater than the specified value? | 0V | |||
12 |
Is the voltage greater than the specified value? | 0V | ||
13 | Repair the short to ground on the 5 V reference circuit. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
14 | With a DVM connected to ground, measure the voltage on the VCM connector terminal GRY 12. Is the voltage greater than the specified value? | 5.2 V | ||
15 | Repair the MAP sensor ground circuit. Refer to Wiring Repairs in Engine Electrical. Is the repair complete? | -- | -- | |
16 | Repair the Sensor Ground Circuit between the VCM and the splice. Refer to Wiring Repairs in Engine Electrical Is the action complete? | -- | -- | |
17 | Repair as necessary. Is the action complete? | -- | -- | |
18 | Replace the EGR valve. Refer to EGR Valve Replacement for the 4.3L. Is the action complete? | -- | -- | |
19 | Repair the short to voltage on the 5 V reference circuit terminal GRY 12. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
20 | Replace the VCM. Important: When replacing the VCM, the new VCM will need to be programmed. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
21 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
22 | Use the scan tool in order to display the Capture Info and the Review Capture Info function. Are any DTCs displayed which were not diagnosed? | -- | Go to The Applicable DTC Table | System OK |
