Jeep Wrangler TJ. Manual — part 163
Symptom:
P0870-OD HYDRAULIC PRESSURE TEST FAILURE
When Monitored and Set Condition:
P0870-OD HYDRAULIC PRESSURE TEST FAILURE
When Monitored:
In any forward gear with engine speed above 1000 RPM shortly after
a shift and every minute thereafter.
Set Condition:
After a shift into a forward gear, with engine speed > 1000 RPM, the TCM
momentarily turns on element pressure to the clutch ckts that don’t have pressure to
identify the correct pressure sw closes. If the pressure sw does not close 2 times the code
sets
POSSIBLE CAUSES
LOSS OF PRIME DTC P0944 PRESENT
RELATED DTC’S PRESENT
INTERMITTENT WIRING AND CONNECTORS
TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
OD PRESSURE SWITCH SENSE CIRCUIT OPEN
OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
INTERNAL TRANSMISSION
TRANSMISSION CONTROL MODULE
377
TRANSMISSION - 42RLE
TEST
ACTION
APPLICABILITY
1
NOTE: Low fluid level can be the cause of many Transmission problems. If
the fluid level is low, locate and repair the leak, then check and adjust the
fluid level per the Service Information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIII
t, read the engine DTC’s. Check and repair all engine DTC’s prior
to performing Transmission Symptom Diagnostics.
With the DRBIII
t, read Transmission DTC’s. Record all DTC’s and 1 Trip Failures.
NOTE: Diagnose 1 Trip Failures as a fully matured DTC.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test
for P0706 Check Shifter Signal.
For Gear Ratio DTC’s, check and record all CVI’s.
Most DTC’s set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
NOTE: Verify flash level of Transmission Control Module. Some problems
are corrected by software upgrades to the Transmission Control Module.
NOTE: Check for applicable TSB’s related to the symptom.
Perform this procedure prior to Symptom diagnosis.
All
Continue
2
With the DRBIII
t, check for other Transmission DTCs.
Is the DTC P0944 present also?
All
Yes
→ Refer to the Transmission category and perform the appropriate
symptom.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 3
3
With the DRBIII
t, read Transmission DTC’s.
Is the DTC P0733 and/or P0871 present also?
All
Yes
→ Replace the Transmission or Solenoid/Pressure Switch Assembly
per the Service Information.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 4
4
With the DRBIII
t, Check the STARTS SINCE SET counter for P0870.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?
All
Yes
→ Go To 5
No
→ Go To 12
378
TRANSMISSION - 42RLE
P0870-OD HYDRAULIC PRESSURE TEST FAILURE —
Continued
TEST
ACTION
APPLICABILITY
5
Turn the ignition off to the lock position.
CAUTION: Remove the Starter Relay. This will prevent the vehicle from
being started in gear.
Install the Transmission Simulator, Miller tool #8333 and the Electronic Transmis-
sion Adapter kit 8333-1A.
NOTE: Check connectors - Clean/repair as necessary.
With the Transmission Simulator, select
9OD9 on the Pressure Switch rotary switch.
With the DRBIII
t, monitor the OD Pressure Switch state while pressing the
Pressure Switch Test button on the Transmission Simulator.
Wiggle the wires leading to the TCM while pressing the test button.
Did the O/D Pressure Switch state change to closed and remain closed while wiggling
the wires?
All
Yes
→ Go To 6
No
→ Go To 7
6
If there are no possible causes remaining, view repair.
All
Repair
Disassemble and inspect the Valve Body per the Service Informa-
tion and repair or replace as necessary. If no problems are found in
the Valve Body, replace the Transmission Solenoid/Pressure
Switch Assembly per the Service Information.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
7
Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the OD Pressure Switch Sense circuit from the TCM
harness connector to the Transmission Solenoid/Pressure Switch Assembly harness
connector.
Is the resistance above 5.0 ohms?
All
Yes
→ Repair the O/D Pressure Switch Sense circuit for an open.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 8
8
Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the OD Pressure Switch Sense circuit.
Is the resistance below 5.0 ohms?
All
Yes
→ Repair the OD Pressure Switch Sense circuit for a short to
ground.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 9
379
TRANSMISSION - 42RLE
P0870-OD HYDRAULIC PRESSURE TEST FAILURE —
Continued
TEST
ACTION
APPLICABILITY
9
Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay.
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the Fused B+ circuit and the Transmission Control
Relay Output circuit in the Transmission Control Relay connector.
Ignition on, engine not running.
Measure the voltage of the OD Pressure Switch Sense circuit.
Is the voltage above 0.5 volt?
All
Yes
→ Repair OD Pressure Switch Sense circuit for a short to voltage.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 10
10
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay.
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the Fused B+ circuit and the Transmission Control
Relay Output circuit in the Transmission Control Relay connector.
Ignition on, engine not running.
Using a 12-volt test light connected to ground, check the Transmission Control Relay
Output circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?
All
Yes
→ Go To 11
No
→ Repair the Transmission Control Relay Output circuit for an open
or high resistance. If the fuse is open make sure to check for a
short to ground.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
11
Using the schematics as a guide, inspect the wiring and connectors. Repair as
necessary. Pay particular attention to all power and ground circuits.
If there are no possible causes remaining, view repair.
All
Repair
Replace the Transmission Control Module per the Service Infor-
mation. WITH THE DRBIII
t PERFORM QUICK LEARN.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
12
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this
circuit.
Wiggle the wiring while checking for shorts and open circuits.
With the DRBIII
t, check the EATX EVENT DATA to help identify the conditions in
which the DTC was set.
Were there any problems found?
All
Yes
→ Repair as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Test Complete.
380
TRANSMISSION - 42RLE
P0870-OD HYDRAULIC PRESSURE TEST FAILURE —
Continued
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