A/T - Diagnostic Procedure
86mitsubishi03SUBJECT:
GALANT AUTOMATIC TRANSMISSION DIAGNOSIS
NO. STB-86-21 -006
DATE August, 1986
MODEL 1985-1986 Galant
PURPOSE This bulletin provides information for diagnosing the operation of the KM 175 automatic transmission used in the 1985 and 1986 Galant.
TOOLS REQUIRED
^ Analog voltmeter
^ Tachometer
^ Jeweler's screwdriver or scratch awl
^ Terminal prying tool (Make from an old screwdriver (Fig. 11) or buy from tool supplier)
DIAGNOSTIC TIPS In diagnosing operating symptoms on the Galant transmission, please be sure always to check the basics first. Check transmission fluid level and condition. Electrical connectors must all be securely connected, and TIPS adjustment is critical to proper operation and driver satisfaction.
To insure a correct diagnosis, immediate correction, and ultimate customer satisfaction, be sure to follow the diagnostic procedure with no changes or shortcuts. The procedures in this bulletin are designed to lead you to a correct, quick, and satisfactory diagnosis which will allow the proper repair for customer satisfaction.
Be sure to review the information contained in STB-84-21-013. Some of the steps in that bulletin are repeated in this one.
Now continue on to the diagnostic procedure beginning on Page 2.
FIGURE 1:
DIAGNOSTIC PROCEDURE
A. BASIC TESTS Perform ALL basic tests 1 through 5 listed below before proceeding further.
1. Check A/T fluid level and condition (Fig. 1). Fluid should be clear and bright red, yellow or light brown, A slight "burned" smell is OK. Add fluid if necessary. Fluid that is dark or opaque, or smells strongly burned or putrid, or contains metal particles is a warning of internal damage to friction elements or contamination in the valve body or solenoids.
FIGURE 2:
2. Check ignition timing. Set if necessary to 8~ BTDC. (5~ BTDC on 1985 models). Fig. 2.
FIGURE 3:
3. Check control cable (inhibitor switch) adjustment. Fig. 3. The engine should start only in N or P. Adjust or replace the switch if necessary.
FIGURE 4:
4. Check the TPS adjustment. (See STB-85-14-002 for TPS adjustment procedure.) It must be between 0.48 and 0.52 volts. Adjust the TPS if necessary to bring voltage output into specified range.
5. Check idle speed. Adjust if necessary to 750 rpm.
FIGURE 5:
B. ELECTRICAL CHECKS
1. Check all connections and wiring to the A/T sensors. See Fig. 5. Connections must be secure and all wiring intact before starting the road test.
FIGURE 6:
2. At the transaxle, disconnect the pulse generator connector. Measure the resistance between pins 1 and 2 (pulse generator A) and pins 3 and 4 (pulse generator B). (Fig. 6.) Resistance should be 245 ohms on cars up to December 1985 and 495 ohms on laterbuilt ones.
FIGURE 7:
3. Under the dash, near the steering shaft, find the 2- pole harness connector for the accelerator switch. Disconnect it and check continuity with a volt/ohmmeter. (Fig. 7.) With accelerator pedal released, resistance should be 0 ohms. Resistance should become infinite when the pedal is depressed 5-8 mm. If switch adjustment is needed, use the adjusting bolt shown-in Fig. 7.
FIGURE 8:
FIGURE 9:
4. At the center console, check all pins and female terminals of the transmission control unit (TCU) connector. Fig. 8. Special tools are under development as this bulletin goes to press. In the meantime, use a terminal inspection tool made from a male spade connector attached to a length of wire. Fig. 9.
FIGURE 10:
Pull-off force must be more than 100g (4 oz.). If pull-off force is small, then the female terminal is loose. Remove the female terminal from the connector body and pry up its center plate to increase spring tension. Fig. 10.
FIGURE 11:
Use a jeweler's screwdriver or a special tool shown in Fig. 11.
FIGURE 12:
5. Disconnect the TCU connector behind the console and, with ignition ON, measure the voltage at the #7 terminal (Red/White) of the body-side half of the connector. With OD switch ON, system voltage should show on the voltmeter. With 0D switch OFF, voltage should be 0. See Fig. 12.
FIGURE 13:
6. Check resistances at the four solenoid connections in Connector A58 behind the battery shown in Fig. 13.
FIGURE 14:
7. With engine fully warmed-up and ignition switch OFF, connect an analog voltmeter (dial-type meter) or ELC Checker to the diagnosis connector behind the glove box. Fig. 14.
8. Turn the ignition switch ON. The voltmeter should deflect periodically, or the ELC Checker indicator light should blink.
9. Start the engine. Under normal conditions, the voltmeter should stop deflecting within 16 sec.
10. Check the continuity at the kickdown switch connector. The engine must be idling; parking brake and foot brake ON. There should be continuity in "D" and "2", and infinite resistance in "L".
FIGURE 15:
11. Water temperature sensor (Fig. 15): check continuity. When coolant temperature is below 50~C. (125~F.), resistance should be infinite (no continuity); when engine coolant is warm, there should be continuity. Resistance should be about 180 ohms.
C. ROAD TEST
1. Increase engine idle speed to 1500 rpm, and shift from P to R. Gear engagement should be firm but not harsh.
2. Check converter stall speed: shift to "D", parking brake and foot brake ON, accelerator wide open. On 1985 models, tachometer should show 2200 rpm plus or minus 200 rpm. On 1986 models, it should be 2350 rpm. If too high, the one-way clutch or the rear clutch is slipping, or line pressure is too low. Repeat in "R"; if too high, the front clutch or low-reverse brake is slipping, or line pressure is too low. CAUTION: Do not exceed 8 seconds for either part of this test!
3. Reduce engine speed to normal idle. Shift from R to N. The shift should be smooth and firm, with no shock.
4. Increase engine speed to 1500 rpm. Shift from N to
D. The shift should be smooth, with no shock.
5. On a level road, at idle in D, release the brake. The car should creep slowly forward.
6. Accelerate to 40 mph at wide-open throttle. There should be a smooth 1-2 upshift at about 35 mph.
NOTE: 1985 models may exhibit a typical slight engine "flare" during the upshift.
7. Hold 45 mph for at least 20 sec. Smooth 2-3 and 3-4 upshifts should be felt.
8. Release the accelerator, and trun off the OD switch The transaxle should downshift to 3rd. Engine speed should increase 900-1000 rpm.
9. Now shift from D to 2. You should feel a downshift, and the tachometer should rise 900-1000 rpm.
10. With accelerator released, shift from 2 to L. The downshift to 1st should occur at about 29 mph.
11. Stop the car, engine idling. Do not turn the engine OFF. Observe the voltmeter for failure codes which may be displayed. See Pages 21-13 and 21-14, 1986 Galant Service Manual for diagnosis of failure codes. MAKE A WRITTEN RECORD OF THE FAILURE CODES.
12. Turn the ignition OFF, and failure codes will be erased.
13. After correcting the condition indicated by the failure code, RETEST THE CAR AS IN STEPS 1-11 ABOVE. NOTE: The transaxle control unit will record only one failure at a time. The road test must be repeated to verity that no additional conditions exist.
D. HYDRAULIC TESTS Perform all hydraulic tests as described in the Service Manual or Service Training Automatic Transmission Repair course materials.
Special Note On Reducing Pressure: Reducing Pressure must be optimized in order to have smooth shifts. The optimum range is 45-47 psi. Adjustment is made by turning a screw in the valve body (See page 21-37 in the 1986 Galant Service Manual). 2-1/2 turns counterclockwise increases reducing pressure by 7 psi.
Note regarding shift quality: Because line pressure on the KM175 is controlled by a solenoid valve (PC solenoid), shift characteristics that in a hydraulicallycontrolled automatic transmission would indicate potential future failure are typical characteristics in the KM175 and not a cause for concern to the technician.