Copyright © 1996 General Motors Corp. 3–27
PREVENTIVE MAINTENANCE
PREVENTIVE MAINTENANCE
A. Abnormal Automatic Shifts (cont’d)
Rough shifting (cont’d) Trimmer valves sticking (broken
spring).
Replace or rebuild main control
valve body assembly. Refer to Para-
graph 6–6.
Control valves sticking. Replace or rebuild main control
valve body assembly. Refer to Para-
graph 6–6.
Modulator valve sticking. Clean modulator valve. Check vac-
uum modulator. Adjust spring. Refer
to Paragraphs 6-6a and 6-6b.
Engine idle speed too fast (N to D). Adjust engine idle screw. Refer to
vehicle service manual.
Shift selector linkage out of adjust-
ment.
Adjust linkage. Refer to the latest
edition of SA1321, AT Mechanic’s
Tips.
No specific shift; i.e., 1–2, 2–3, 3–4
(up or down)
Governor valve malfunctioning. Clean or replace governor screen
and/or governor. The governor may
be disassembled for cleaning and
inspection only if the kit consisting
of two governor weight pins and
cover gasket is available. Refer to
Paragraphs 5–3e, 5–3h(5), 6–5,
7–10a, and 7–11a.
Specific range valves malfunction-
ing (sticking).
Replace or rebuild main valve body
assembly. Refer to Paragraph 6–6.
Shift flare during range shifts, AT
545 models only.
Incorrect trimmer valves installed. Replace trimmer valves. Refer to
Paragraph 6–6a(9).
B. Abnormal Activities or Responses
Excessive creep in first range and
reverse
Engine idle speed set too high. Adjust to correct idle speed. Refer to
vehicle service manual.
Shift selector linkage unhooked. Hook up shift selector linkage —
quadrant gates must agree with
transmission model. Detent posi-
tions at transmission must conform
with gates on quadrant. Refer to
vehicle service manual and to the
latest edition of SA1321, AT
Mechanic’s Tips.
Table 3–13. Troubleshooting Chart (cont’d)
Problem Probable Causes Suggested Remedies
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