DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Cadillac Concours 1997

For 1990-2009 cars

### DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Engine Controls Components
IAT/ ECT/ TP/ MAP and BBV Sensors
OBD II Symbol Description Notice
ESD Notice
ESD Notice

### Circuit Description

The Throttle Position sensor is potentiometer. A 5 volt reference is provided on CKT 605 and ground is provided on CKT 808. The TP sensor signal CKT 417 varies between ground and 5 volts based on the position of the throttle plates. At low throttle angle, the TP sensor signal voltage is low. The PCM uses TP sensor information to determine idle, Wide Open Throttle (WOT), deceleration enleanment and acceleration enrichment. DTC P0122 sets when the PCM detects a TP sensor signal that is too low. The PCM tests the TP sensor feedback every 100 ms. If the TP sensor reading is 0.1 volts or less, such as when the signal is open or shorted to ground, the PCM sets DTC P0122.

### Conditions for Setting the DTC

#### Test Condition

Engine speed 600 RPM or greater.

#### Failure Condition

The TP sensor reading is 0.1 volts or less.

### Action Taken When the DTC Sets

• | PCM disables the torque converter clutch.

• | PCM calculates a TP sensor value based on MAP and engine speed inputs.

• | PCM disables fourth gear.

• | The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

• | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

• | A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.

• | Use a scan tool to clear DTCs.

• | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

### Diagnostic Aids

If fault is not present perform Powertrain Ground Check and also review Failure Rec. to determine conditions under which and how long ago the DTC set.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. With TP sensor or wiring open, TP sensor display will read 0.1 volts or less.

2. Checking for open TP sensor or open wiring. If the display value stays less than 4.96 volts with the TP sensor terminals A and C jumpered together, the problem is in the wiring.

3. Voltage should be greater than 0.5 volt if CKT 605 is not open or shorted to ground.

4. If voltage at TP sensor connector terminal A is 4.5 volts or more, the TP Sensor Signal circuit could be shorted to ground.

5. Use the MAP display to determine if a 5 volt reference problem exists.

6. If there is high resistance, the TP Sensor Signal circuit could be open. If low resistance exists the PCM may be faulty.

7. Checking the 5 volt reference feed to the TP sensor.

   The 5 volt reference circuits are shared inside the PCM. A short to ground on any 5 volt circuit will cause several other 5 volt circuits to be grounded also. A short to ground may also occur in one of the components that uses a 5 volt reference.

   Check for shorted components before replacing a PCM.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check

2

1. Turn the key ON,
2. Using a scan tool view the TP display.

Does throttle position read the same or less than the value specified?

0.1 volts

Go to Step 3

Fault not present. Refer to Diagnostic Aids

3

1. Disconnect throttle position sensor connector.
2. Jumper terminal A to C (harness side).

Does TP display read the same or more than the value specified?

4.5 volts

Go to Step 13

Go to Step 4

4 | Using DMM J 39200 measure voltage to ground on jumper. Is voltage less than the value specified? | 0.5 volts | Go to Step 5 | Go to Step 7

5

1. Remove jumper.
2. Measure voltage to ground at throttle position sensor connector terminal A (harness side).

Is voltage the same or more than the value specified?

4.5 volts

Go to Step 9

Go to Step 6

6 | Using a scan tool view the MAP display. Does MAP sensor display read the same or less than the value specified? | 17 kPa | Go to Step 8 | Go to Step 10

7

1. Record the fluid life indexes, turn the key to LOCK and wait 30 seconds.
2. Disconnect PCM connector C1.
3. Measure the resistance between PCM connector C1 terminal 68 and throttle position sensor connector terminal C (harness side).

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 15

Go to Step 11

8

1. Record the fluid life indexes, turn the key to LOCK and wait 30 seconds.
2. Disconnect PCM connector C2.
3. Disconnect the MAP and BBV sensors and the EGR valve.
4. Measure the resistance to ground on PCM connector C1 terminals 62, 63, 64 and 65. Refer to Test Descriptions.

Is either CKT less than the value specified?

10K ohms

Go to Step 12

Go to Step 15

9 | Repair the short to engine ground in the TP Sensor signal circuit or the signal circuit shorted to the ground circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --
10 | Repair the open in the 5 Volt Reference circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --
11 | Repair the open in the TP Sensor Signal circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --
12 | Repair the short to ground on CKT(s) with low resistance. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --

13

1. Check terminal contact at the Throttle Position sensor.
2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 14

14 | Replace the Throttle Position sensor. Refer to TP Sensor Replacement . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --

15

1. Check terminal contact at the PCM connector C1 terminals 63 and 68.
2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 16

16 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --