TRANSMISSION SYSTEM
DIAGNOSTIC FLOWCHART
(4L80-E)
TM 9-2320-280-20-1
2-428
Change 1
NOTE
• The following diagnostics will help isolate and
repair problem circuits, wires, pins, connectors,
sensors, circuit breakers, and solenoids.
• For repair of all wiring, refer to para. 4-85.
• Check connector pins before inserting probes.
No
No
No
No
No
Go to pg 2-431
Go to pg 2-430
Go to pg 2-432
Go to pg 2-433
Go to pg 2-433
Go to pg 2-434
J1 Voltage Measurements With Ignition ON, Engine OFF,
and Glow Plug Controller Disconnected. Refer to para 4-29.
CKT NOM.
CKT #
PIN
TO
PIN
EXP READ
IGN PWR
291D
j
a or b
12VDC
Battery Pos
537D
Z
a or b
12VDC
Trans Lp
657A
U*
a or b
LED Lights
Brake Sw
810B
W
a or b
12V (Brake OFF)
Brake Sw
810B
W
a or b
O (Brake ON)
* Jumper wire from U to a or b.
Reconnect Glow Plug Controller; refer to para 4-29.
J1 Voltage Measurement With Ignition ON, Engine ON,
and Transmission in PARK.
CKT NOM.
CKT #
PIN
TO
PIN
EXP READ
Engine RPM
349A
h
c or p
0.3 Volts
min @ idle
Press SW A
765A
A
a or b
Open wire
Press SW B
763A
B
a or b
0 to 1 ohms
Press SW C
764A
C
a or b
Open wire
J1 CABLE DIAGNOSTICS CHART
No
No
No
Go to pg 2-442
Go to pg 2-442
Go to pg 2-442
