MIL ON DTC P0120 Throttle Position (TP) Circuit Defect
NO: TSB-99-13-008DATE: October, 1999
MODEL: See below
SUBJECT:
DTC P0120 DIAGNOSIS
This bulletin supersedes TSB-98-13-014, issued December, 1998. Mirage models have been deleted from this bulletin, as this condition can be corrected on 1.5L and 1.8L Mirages by reprogramming the PCM as described in TSB-99-13-007. The revised information is marked by "**".
PURPOSE
On some affected vehicles, the powertrain control module (PCM) may cause the "SERVICE ENGINE SOON" light to come on. Diagnostic Trouble Code DTC P0120 "Throttle Position Circuit Malfunction" may also set in the PCM.
If the PCM has previously been reprogrammed for this condition or if the vehicle was originally equipped with the latest PCM programming, perform the diagnosis instructions in Group 13 of the appropriate service manual for DTC P0120. If the PCM has not been previously reprogrammed and the TPS operates normally, replace the PCM.
AFFECTED VEHICLES
1999 Montero Sport 2.4L models produced before 9/10/98
1999 Montero Sport 3.0L manual transmission models produced before 8/29/98
1999 3000GT SOHC and DOHC models produced before 8/25/98
1999 3000GT DOHC turbocharged (VR-4) models produced before 8/9/98
1999 Montero models produced before 8/25/98
**IMPORTANT:
This bulletin does NOT apply to 1.5L and 1.8L Mirage models. Refer to TSB-99-13-007 for PCM reprogramming instructions for these models.
NOTE:
This bulletin does not apply to 1999 Galant and Eclipse. Refer to TSB-98-13-013REV for these models.
PROCEDURE
1. Using the MUT-II scan tool, check to see if any DTCs are set in the PCM. If any DTC except DTC P0120 is set, follow the appropriate troubleshooting and repair instructions in the service manual. Then go to Step 2.
2. Inspect the underhood of the vehicle for an Engine Compartment label.
a. If there is a label indicating that this TSB has already been completed, refer to the diagnosis instructions for DTC P0120 in Group 13 of the appropriate service manual. Do not continue with this procedure.
b. If there is not a label indicating that this TSB has already been completed, verify the PCM software level by either checking the vendor number on the PCM label, or by checking the ROM ID with the MUT-II scan tool.
(1) If checking on the PCM label: If the vendor number is lower than the vendor number in the chart in the PARTS INFORMATION section of this bulletin, continue with Step 3.
(2) If checking with the MUT-II scan tool: Connect the scan tool to the vehicle and perform the following selection sequence:
c. If the ROM ID is as shown, or if the PCM vendor number is as specified in the PARTS INFORMATION section of this bulletin, refer to the diagnosis instructions for DTC P0120 in Group 13 of the appropriate service manual. Do not continue with this procedure.
3. Confirm proper TPS operation as follows:
a. Turn the ignition key ON. On the MUT-II screen, check the MFI data list for TPS voltage. Confirm that the TPS voltage is within service manual specifications at closed throttle and at wide open throttle. Also confirm that the voltage changes smoothly as the throttle is opened and closed.
b. If the TPS voltage reading is not within specification or its voltage changes erratically, refer to the diagnosis instructions for DTC P0120 in Group 13 of the appropriate service manual.
c. If the TPS voltage reading is within specifications and its voltage changes smoothly, go to step 4.
4. Replace the PCM as described in the appropriate service manual. Refer to the PARTS INFORMATION listing in this bulletin.
IMPORTANT
a. Check the replacement PCM vendor number before installing. The PCM part number not changed with the software update. The vendor number on the PCM label reflects whether the PCM software has been updated. Verify that the PCM has the latest software by comparing the vendor number on the PCM label with the vendor number in the chart in the PARTS INFORMATION section of this bulletin.
b. Prepare an Engine Compartment Label (part number MSSF-023G-00A) by entering the appropriate PCM part number, vendor number, this TSB number (TSB-99-13-008), your dealer code, and the current date. (Write in the vendor number beside the part number as shown.)
If a partially complete Engine Compartment Label was provided with the replacement PCM, enter your dealer code and the current date on the label.
c. Carefully remove all dirt and oil from the vacant area shown on the underside of the hood. Affix the Engine Compartment label in the appropriate area shown:
PARTS INFORMATION
WARRANTY INFORMATION
Standard warranty procedures, labor operations, and times apply.