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connectors and terminals are okay, measure resistance between ground
and 3-4 shift solenoid control circuit at PCM harness connector. If
resistance is 5 ohms or greater, go to next step. If resistance is
less than 5 ohms, repair short to ground in 3-4 shift solenoid
circuit.
6) Measure resistance of 3-4 shift solenoid circuit between
White PCM harness connector C2 and transmission solenoid harness
connector. If resistance is 5 ohms or greater, repair open 3-4 shift
solenoid circuit. If resistance is less than 5 ohms, go to next step.
7) Turn ignition on. Measure voltage between ground and 3-4
shift solenoid control circuit at PCM harness connector. If voltage is
greater than one volt, repair 3-4 shift solenoid control circuit for
short to voltage. If voltage is one volt or less, go to next step.
8) Turn ignition off. Remove transmission control relay.
Inspect transmission control relay connector and terminals for damage.
Repair as necessary. If connector and terminals are okay, measure
resistance between transmission control relay output circuit at
transmission control relay connector and 3-4 shift solenoid control
circuit at White PCM harness connector C2. If resistance is 26-40
ohms, go to next step. If resistance is not 26-40 ohms or less,
replace 3-4 shift solenoid.
9) Measure resistance between ground and transmission control
relay output circuit at transmission control relay connector. If
resistance is less than 5 ohms, repair short to ground in transmission
control relay output circuit. If resistance is 5 ohms or greater, go
to next step.
10) Measure resistance between transmission control relay
output circuit between transmission control relay connector and
transmission solenoid harness connector. If resistance is 5 ohms or
greater, repair open transmission control relay output circuit. If
resistance is less than 5 ohms, go to next step.
11) Turn ignition on. Measure voltage between ground and
fused B+ circuit at transmission control relay connector. If voltage
is 10 volts or less, repair open fused B+ circuit. If voltage is
greater than 10 volts, replace PCM.
12) Disconnect transmission control relay. Inspect connector
and terminals for damage. Repair as necessary. If connector and
terminals are okay, turn ignition on. Replace transmission control
relay. Using scan tool, actuate transmission control relay. Measure
voltage between ground and transmission relay output circuit at
transmission solenoid harness connector. If voltage is greater than 10
volts, replace transmission control relay. If voltage is 10 volts or
less, go to next step.
13) Measure resistance of transmission control relay output
circuit between transmission control relay connector solenoid harness
connector. If resistance is 5 ohms or greater, repair open in
transmission control relay output circuit. If resistance is less than
5 ohms, go to next step.
14) Measure resistance of transmission control relay output
circuit between ground and transmission control relay connector. If
resistance is 5 ohms or greater, go to next step. If resistance is
less than 5 ohms, repair short to ground in transmission control relay
output circuit.
15) Turn ignition on. Measure voltage between ground and
fused B+ circuit at transmission control relay connector. If voltage
is 10 volts or less, repair open fused B+ circuit. If voltage is
greater than 10 volts, test is complete.
16) Using scan tool, erase DTCs. Start engine. Attempt to
duplicate data and reset code. Using wiring diagram as a guide,
inspect wiring and connectors. Repair wiring harness as necessary. If
wiring and connectors are okay, wiggle wiring harness between TCC
solenoid and PCM. Note if DTC P0753 resets. If DTC P0753 resets,
repair wiring harness as necessary. If DTC P0753 does not reset,
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replace PCM and see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
DTC P0783: 3-4 SHIFT SOL, NO RPM DROP @ 3-4 SHIFT
Circuit Description
Circuit is monitored continuously while key is on and engine
running. Code sets if expected RPM drop does not occur within 4
seconds of requested gear change by PCM. Test must fail 3 times to set
code.
Possible Causes
* Transmission mechanically defective.
* TPS codes set.
* Transmission 3-4 solenoid wiring harness defective.
* Transmission fluid burnt or oil pan has excessive debris.
Diagnostic Procedures
1) Using scan tool, read DTCs. On all bodies except AB and WJ
bodies, go to next step. On AB and WJ bodies, if DTC SPECIFIC GOOD
TRIPS counter is not displayed or displayed count is not "0", go to
step 6). If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", indicating DTC still exists, go to next step.
2) If any DTCs listed are present, perform appropriate
test(s). See 3-4 SHIFT SOLENOID TESTS table. If no DTCs are present,
go to next step.
3-4 SHIFT SOLENOID TESTS
\
\
\
\
\
\
\
DTC Message Test
NO CAM SIGNAL AT PCM ..................................... ( 1) P0340
P/N SWITCH STUCK IN PARK OR IN GEAR .......................... P1899
Any Throttle Position Sensor (TPS) DTC ......................... ( 1)
TORQUE CONVERTOR CLUTCH SOLENOID/TRANS RELAY CIRCUITS ........ P0743
TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT ..................... P1765
TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS ................ P0753
( 1) - See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
\
\
\
\
\
\
\
3) Check transmission fluid for proper level and for any
debris. Fill or repair transmission as necessary. If fluid level and
condition are okay, go to next step.
4) Connect a 0-300 psi (0-21 kg/cm
) pressure gauge to
transmission Overdrive (O/D) clutch pressure test port. Connect a
second 0-300 psi (0-21 kg/cm
) pressure gauge to transmission governor
pressure test port. See appropriate AUTOMATIC TRANSMISSION OVERHAUL
article. Ensure engine and transmission are at normal operating
temperature. With an assistant, test drive vehicle. Using scan tool,
select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear while
monitoring pressure gauge. Governor pressure should rise to greater
than 20 psi (1.4 kg/cm
) and O/D pressure should rise to greater than
40 psi (2.8 kg/cm). If pressures are as specified, go to next step.
If pressures are not as specified, go to step 8).
5) Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, go to next step.
6) Using scan tool, erase DTCs. Start engine. Road test
vehicle at 0-55 MPH with a constant 20 percent throttle. Repeat road
test 4 times. Note if DTC P0783 resets. If DTC P0783 resets, repair
wiring harness as necessary. If DTC P0783 does not reset, go to next
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step.
7) Turn engine off. Drain transmission fluid and remove oil
pan. Inspect oil pan for burnt oil and debris. Repair transmission as
necessary. See appropriate AUTOMATIC TRANSMISSION OVERHAUL article. If
transmission is okay, no problem is found at this time, see INACTIVE
DTC CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
8) Leave gauges connected. Replace 3-4 shift solenoid.
Replace transmission pan and fill with fluid. Start engine and allow
engine and transmission to reach normal operating temperature. Using
scan tool, select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear
while monitoring pressure gauges. Governor pressure should rise to
greater than 20 psi (1.4 kg/cm
) and O/D pressure should rise to
greater than 40 psi (2.8 kg/cm). If pressures are as specified, no
problem is found at this time. Testing is complete. If pressures are
not as specified, see appropriate AUTOMATIC TRANSMISSION OVERHAUL
article, paying attention to seals and clutches related to O/D clutch.
DTC P1740: TCC OR O/D SOLENOID PERFORMANCE (BR BODY - DIESEL)
Circuit Description
Torque Converter Clutch (TCC) and overdrive clutch are tested\
when Powertrain Control Module (PCM) requests TCC engagement in 3rd
gear and overdrive. Code will set if expected RPM drop is not achieved
while attempting to engage TCC and/or overdrive. Code indicates
malfunctioning torque converter or overdrive clutch.
Possible Causes
* Fluid level or quality problem.
* Transmission wiring and connector defective.
* Transmission mechanically defective.
* Low fuel level.
* Trans temperature below 32
.
* Transfer case is in low range.
* Engine RPM trouble codes set.
* Misfire trouble code set (DTCs P0300-P0306).
* Output shaft speed trouble code set.
* PTO is engaged.
* TPS codes set (DTCs P0121-P0123).
* Torque converter defective.
Diagnostic Procedures
1) Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to step
16). If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", go to next step.
2) If any DTCs listed are present, perform appropriate
test(s). See TCC OR O/D SOLENOID TESTS table. If no DTCs are present,
go to next step.
TCC OR O/D SOLENOID TESTS
\
\
\
\
\
\
\
DTC Message Test
CAMSHAFT POSITION SENSOR SIGNAL .......................... ( 1) P0341
P/N SWITCH STUCK IN PARK OR IN GEAR .......................... P1899
Any Throttle Position Sensor (TPS) DTC ......................... ( 1)
Any Misfire DTC ................................................ ( 1)
Any Engine RPM DTC ............................................. ( 1)
Any Output Shaft Speed Sensor DTC .............................. ( 1)
TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT ..................... P1765
TORQUE CONVERTOR CLUTCH SOLENOID/TRANS RELAY CIRCUITS ........ P0743
TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS ................ P0753
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