Toyota
Jeep Cherokee
 Service Manual
Transmission and transfer case » Automatic transmission-30RH » Diagnosis and testing
Preliminary diagnosis

Two basic procedures are required. One procedure for vehicles that are drivable and an alternate procedure for disabled vehicles (will not back up or move forward).

VEHICLE IS DRIVEABLE

(1) Check for transmission fault codes using DRB scan tool.

(2) Check fluid level and condition.

(3) Adjust throttle and gearshift linkage if complaint was based on delayed, erratic, or harsh shifts.

(4) Road test and note how transmission upshifts, downshifts, and engages.

(5) Perform stall test if complaint is based on sluggish acceleration. Or, if abnormal throttle opening is needed to maintain normal speeds with a properly tuned engine.

(6) Perform hydraulic pressure test if shift problems were noted during road test.

(7) Perform air-pressure test to check clutch-band operation.

VEHICLE IS DISABLED

(1) Check fluid level and condition.

(2) Check for broken or disconnected gearshift or throttle linkage.

(3) Check for cracked, leaking cooler lines, or loose or missing pressure-port plugs.

(4) Raise and support vehicle on safety stands, start engine, shift transmission into gear, and note following: (a) If propeller shaft turns but wheels do not, problem is with differential or axle shafts.

(b) If propeller shaft does not turn and transmission is noisy, stop engine. Remove oil pan, and check for debris. If pan is clear, remove transmission and check for damaged drive plate, converter, oil pump, or input shaft.

(c) If propeller shaft does not turn and transmission is not noisy, perform hydraulic-pressure test to determine if problem is hydraulic or mechanical.

    More about «Diagnosis and testing»:

    Automatic transmission diagnosis

    Effects of incorrect fluid level

    Causes of burnt fluid

    Fluid contamination

    Preliminary diagnosis

    Park/neutral position switch

    Gearshift cable

    Throttle valve cable

    Road testing

    Analyzing road test

    Hydraulic pressure test

    Air testing transmission clutch and band operation

    Converter housing fluid leak diagnosis

    Diagnosis charts

    Jeep Cherokee Service Manual / Transmission and transfer case / Automatic transmission-30RH / Diagnosis and testing / Preliminary diagnosis

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