A/T - KM171 &, KM172 Surge
87mitsubishi01SUBJECT:
KM171, KM172 TRANSMISSIONS - ELC SURGE
NO. STB-87-21-003 REVISION
DATE September, 1987
MODEL 1987 Cordic/Tredia, Mirage, Precis
NOTE: This bulletin supersedes STB-87-21-003 dated May, 1987 which is incomplete and should be discarded. The Precis model has been added and the torque specifications for the valve body components have been corrected.
PURPOSE
This bulletin describes parts and procedures for correcting a surge in the automatic transmission of Cordia/Tredia, Mirage and Precis vehicles.
VEHICLES AFFECTED
^ Cordia/Tredia, Mirage with A/T built before January 1987 beginning with transaxle No. CM5762.
^ Precis with A/T built before April 1987 beginning with transaxle No. CM5762.
SYMPTOM
When driving at a steady speed, the engine speed fluctuates by 100-200 rpm and a light surge is felt as engine speed increases and decreases.
CAUSE
The surge is caused by incomplete engagement of the torque converter damper clutch due to variations in transmission fluid pressure from the lock up control solenoid valve at light loads.
FIGURE 1:
FIGURE 2:
FIGURE 3:
FIGURE 4:
DIAGNOSIS
Make sure the surge is not caused by the EGR. There are two ways you can check for the EGR surge.
The first way is: after driving the car to feel the surge, disconnect the Yellow/Red wire (Cordia/Tredia & Mirage) from the thermo switch terminal (Figs. 1 & 2), or the Yellow/Green and Yellow/Red wires (Precis) from the coolant temperature sensor (Fig. 3) and drive the car again. If the surge was
eliminated, it was caused by the damper clutch. The second way is to test the damper clutch control solenoid voltage. To do this you will need a 12V analog voltmeter and a 6V lantern battery. Connect the voltmeter into the large connector of the TCU on the left control side panel. The (+) probe of the voltmeter goes into the cavity with the Light Green wire. The (-) probe goes to the ground (The Black wire in the connector is a ground wire.) See Fig. 4.
Place the voltmeter where it can be seen while driving. Drive the car. A voltage reading of less than 3V is normal. In third gear, at approximately 30 mph under light load, the voltage should fluctuate between 0.5 and 2.0 volts about 40-60 times per minute. This indicates that the ELC is working.
Now have an assistant connect the 6V battery across the Lg and Black termninals. If this eliminates the surge, you know it is the ELC and not the EGR or something else.
Refer to the following diagnostic chart for more information.
PARTS INFORMATION
A Lower Valve Body Repair Kit, MD728159 (Cordia/Tredia, Mirage) or 4F701-21720 (Precis), is available for installation. This kit is interchangeable as a complete unit, but the individual parts are not interchangeable.
FIGURE 5:
PARTS DESCRIPTION
1. Damper Clutch Control Valve: The diameters of the valve lands have been changed. See Fig. 5.
FIGURE 6:
2. Damper Clutch Sleeve: The inner diameter of the sleeve has been changed. See Fig. 6.
3. Damper Clutch Control Valve Spring: The spring force has been changed. The old force was 0.9 lbs. at 9.88 mm; the newforce is 2.3 lbs. at 9.8 mm.
FIGURE 7:
4. Solenoid Valve: The electrical terminal has been repositioned as shown in Fig. 7.
FIGURE 8:
5. Lower Valve Body. The hole diameter for the damper clutch control valve has been changed. See Fig. 8.
FIGURE 9:
CORRECTIVE PROCEDURE
1. Obtain Lower Valve Body Kit MD728159 (Cordia/Tredia, Mirage) or 4F701-21720 (Precis) (Fig. 9).
2. Remove the valve body. This can be done without removing the transaxle from the vehicle.
FIGURE 10:
3. Separate the lower valve body and separator plate from the valve body. Hold the separator plate against the lower valve body to keep the stopper plate from falling out of the lower valve body (Fig. 10).
FIGURE 11:
4. Remove parts to be transferred from the old lower valve body (Fig.11).
5. Install the new parts from the kit in the new lower valve body. Install the parts transferred from the old valve body.
NOTE: All parts must be cleaned and lubricated with ATF.
6. Reinstall the end cover and tighten the attaching screws to 43-60 inch-pounds (3.6- 5.0 foot-pounds).
FIGURE 12:
7. If the stopper plate has not yet been installed, install it now (Fig. 12).
8. Assemble the two halves of the valve body and the separator plate. Install the screws and tighten them to 43-60 inch-pounds (3.6-5.0 foot-pounds).
FIGURE 13:
9. Remove the old solenoid valve and install the new one (Fig. 13). Tighten the mounting screws to 43-60 inch-pounds (3.6-5.0 foot-pounds).
10. Reassemble the valve body to the transmission, install the filter and oil pan, refill with Dexron II ATF, and test the transmission.
WARRANTY INFORMATION
CORDIA/TREDIA AND MIRAGE VEHICLES:
Labor Operation Code:
21 95 10 90
Time Allowance: 1.3 hr.
PRECIS VEHICLES:
Labor Operation Code:
45 60 OR 00
Time Allowance: 1.2 hr.
Please enter these claims as "W" claims through menu selection "W2" on your Diamond Network Warranty System.