Jeep Wrangler TJ. Manual — part 173
Symptom:
P1790-FAULT IMMEDIATELY AFTER SHIFT
When Monitored and Set Condition:
P1790-FAULT IMMEDIATELY AFTER SHIFT
When Monitored:
After a speed ratio error is stored.
Set Condition:
This code is set if the associated speed ratio code is stored within 1.3
seconds after a shift.
POSSIBLE CAUSES
CONDITION P1790 PRESENT
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
This DTC is set along with a gear ratio DTC. Perform the appropriate test for the
Gear Ratio DTC stored.
NOTE: Check 1 trip failures if there are no Gear Ratio DTC’s current.
If there are no possible causes remaining, view repair.
All
Repair
Refer to the Transmission category and perform the appropriate
symptom.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
417
TRANSMISSION - 42RLE
Symptom:
P1793-TRD LINK COMMUNICATION ERROR
When Monitored and Set Condition:
P1793-TRD LINK COMMUNICATION ERROR
When Monitored:
The transmission controller pulses the 12 volt TRD signal from the
PCM to ground, during torque managed shifts with the throttle angle above 54 degrees.
The TRD system is also tested whenever the vehicle is stopped and the engine speed is at
idle.
Set Condition:
This code is set when the Transmission Control Module (TCM) sends two
subsequent torque reduction messages to the Powertrain Control Module (PCM) via the
TRD link circuit and does not receive a confirmation from the PCM over the communica-
tion bus.
POSSIBLE CAUSES
RELATED DTC’S PRESENT
TORQUE MANAGEMENT REQUEST SENSE CIRCUIT OPEN
TORQUE MANAGEMENT REQUEST SENSE SHORT TO GROUND
TORQUE MANAGEMENT REQUEST SENSE CIRCUIT SHORT TO VOLTAGE
POWERTRAIN CONTROL MODULE
TRANSMISSION CONTROL MODULE
INTERMITTENT WIRING AND CONNECTORS
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
418
TRANSMISSION - 42RLE
TEST
ACTION
APPLICABILITY
2
With the DRBIII
t, read Transmission DTC’s.
Are any of the following DTCs P1694, P0731, P0732, P0733, P0734, P0736 present
also?
All
Yes
→ If any of these codes are present, disregard the P1793 DTC and
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, Check the STARTS SINCE SET counter.
Note: This counter only applies to the last DTC set.
Is the STARTS SINCE SET equal to 0?
All
Yes
→ Go To 4
No
→ Go To 9
4
Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the TCM harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Torque Management Request Sense circuit from the
TCM harness connector to the PCM harness connector.
Is the resistance above 5.0 ohms?
All
Yes
→ Repair the Torque Management Request Sense circuit for an
open.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 5
5
Turn the ignition off to the lock position.
Disconnect the PCM harness connector.
Disconnect the TCM harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the Torque Management Request Sense
circuit.
Is the resistance below 5.0 ohms?
All
Yes
→ Repair Torque Management Request Sense circuit for a short to
ground.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 6
6
Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Ignition on, engine not running.
Measure the voltage of the Torque Management Request Sense circuit.
Is the voltage above 10.5 volts?
All
Yes
→ Repair Torque Management Request Sense circuit for a short to
voltage.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 7
419
TRANSMISSION - 42RLE
P1793-TRD LINK COMMUNICATION ERROR —
Continued
TEST
ACTION
APPLICABILITY
7
Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Ignition on, engine not running.
Measure the voltage of the Torque Management Request Sense circuit in the TCM
harness connector.
Is the voltage above 7.0 volts?
All
Yes
→ Replace the Transmission Control Module per the Service Infor-
mation. WITH THE DRBIII
t PERFORM QUICK LEARN.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
No
→ Go To 8
8
If there are no possible causes remaining, view repair.
All
Repair
Replace and program the Powertrain Control Module per the
Service Information.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER
1.
9
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.
420
TRANSMISSION - 42RLE
P1793-TRD LINK COMMUNICATION ERROR —
Continued
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