Service slants

Motor,  May 2003  by Savasta, Bob

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Chrysler

MIL illuminated, DTC 21 set.

Some 1995 Dodge/Plymouth Neons built before 4/5/94 may illuminate the MIL with DTC 21 (upstream or downstream oxygen sensor shorted to voltage) logged in computer memory. Begin your diagnosis by scanning the engine management system. If nothing looks unusual in the data stream and DTC 21 is the only code that has been stored in memory, the PCM most likely needs to be reprogrammed. If the code is still present after the computer has been zapped, Chrysler says to follow through with normal diagnostics for a shorted O2 sensor.

Dodge Truck/Jeep

MIL illuminates erroneously, DTC P0107 set. Some 1996-98 Dodge trucks and Jeeps (full vehicle list below) that erroneously illuminate their MIL while setting DTC PO107 (MAP sensor voltage too low) in computer memory are candidates for a flash reprogramming of the PCM. According to Chrysler, the problem occurs during downhill decelerations at altitude or when performing off-road maneuvers with the engine operating above 1500 rpm. The MIL illuminates due to the component monitor running at the wrong parameters.

Begin the fix by recording and addressing any DTCs other than P0107. Clear the computer memory, then see if the MIL comes back on during the driving conditions outlined above. If it does and P0107 resets, flash the PCM with one of the following three calibration changes: 96 Cal 18, 97 Cal 18 or 98 Cal 12. Note: The reprograrmning procedure may cause DTCs to set in other vehicle modules (EATX, BCM, MIC, etc.). All will relate to a loss of communication between that module and the PCM. Record all codes, then clear them before releasing the vehicle to the customer.

The following vehicles are covered by the above repair:

1996-98 Dodge Ram

Trucks, Dakotas & Ram Vans

1996-98 Jeep

Cherokees & Grand Cherokees

1997-98 Jeep

Wranglers

Acura

Knocking noise over bumps. Some 1996-98 3.5RL models may exhibit a knocking noise from the front suspension when going over bumps or irregular road surfaces. Wear in the upper control arm bearing (part of the front anchor bolt assembly) is the likely cause. To nail the diagnosis, test-drive the vehicle to determine where the noise is coming from. If its from the front end, get back to your shop and raise the car on a lift. Next, go to the corner of the car you think is making the noise, reach in over the tire and place your hand over one of the upper arm bearings. Now, hit the upper portion of the tire sharply several times with a large mallet. Repeat the procedure for the other bearing. If you feel looseness in the bearing(s) or hear a knocking sound, replace the anchor bolt(s) with a revised design, Part No. 51010-SZ3-000.

Toyota

MIL illuminated, DTC P1133 set.

Owners of 1997-99 Camrys and 1999 Solaras with California-spec 5S-FE engines may express concern because their MIL is on. If hooking up your scanner reveals DTC Pl 133 (oxygen sensor circuit response) in PCM memory, proceed with normal diagnostics for the code as outlined in a repair manual. If that proves fruitless, it could be that the air/fuel ratio sensor (Toyota's linear O2 sensor) has gone belly-up. Installing a new-design sensor (Part No. 89467-33011) should solve the problem.