Hummer H1 (2002+). Manual — part 79
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Transmission/Transfer Case 5-115
®
05745159
9
Replace the PCM. Refer to
PCM Replacement/Pro-
gramming
, Section 6.
Is the replacement complete?
—
Go to Step 17
—
10
1.
Disconnect the internal wiring harness at the TCC
PWM Sol. Valve.
2.
Measure the resistance of the TCC PWM Sol.
Valve.
Is the resistance within the specified values?
10-15
Go to Step 12
Go to Step 15
11
Measure the resistance between terminal E and ground
and terminal S and ground.
Are both readings greater than the specified value?
250
Go to Diag-
nostic Aids
Go to Step 13
12
Inspect the internal wiring harness for an open circuit.
Refer to Electrical Diagnosis, Section 8.
Did you find a problem?
—
Go to Step 16
—
13
1.
Disconnect the internal wiring harness at the TCC
PWM Sol. Valve.
2.
Measure the resistance between each of the com-
ponent terminals and ground.
Are both readings greater than the specified value?
250
Go to Step 14
Go to Step 15
14
Inspect the internal wiring harness for a short to
ground. Refer to Electrical Diagnosis, Section 8
Did you find a problem?
—
Go to Step 16
—
15
Replace the TCC PWM Sol. Valve. Refer to 4L80-E
On-Vehicle Service.
Is the replacement Complete?
—
Go to Step 17
—
16
Replace the Automatic Transmission Wiring Harness
Assembly (A/T Wiring Harness Assy). Refer to 4L80-E
On-Vehicle Service.
Is the replacement complete?
—
Go to Step 17
—
17
In order to verify your repair, perform the following
procedure:
1.
Select DTC.
2.
Select Clear Info.
3.
Operate the vehicle under the following conditions:
• The TCC PWM Sol. Valve is commanded ON
and the volts drop to zero.
• The TCC PWM Sol. Valve is commanded OFF
and the volts increase to B+.
• All conditions are met for 5 seconds.
4.
Select Specific DTC. Enter DTC P1860.
Has the test run and passed?
—
System OK
Begin the
diagnosis
again. Go to
Step 1
DTC P1860 Torque Converter Clutch Pulse Width Modulation Solenoid Electrical (Cont’d)
Step
Action
Value
Yes
No
5-116
Transmission/Transfer Case
___________________________________________
®
DTC P1870 Transmission Component Slipping
Circuit Description
The PCM monitors the difference in engine speed and trans-
mission input speed. In D3 drive range with the converter
clutch engaged, engine speed should closely match transmis-
sion output speed. In D4 drive range with the converter clutch
engaged, clutch slip speed should be between -20 and +20 rpm.
This DTC detects excessive slip when the converter clutch is
engaged.
Conditions For Setting DTC
The following conditions are met for 10 seconds with 4th gear
commanded.
• No engine speed DTC P0335.
• No DTCs P0121, P0122, P0123, P0220,P0221, P0222,
P0223, P0225, P0226, P0227, P0228.
• No DTCs P0716 or P0717.
• No DTC P0722 or P0723.
• No DTCs P0741, P0742 or P0719.
• No shift solenoid 1-2 DTCs P0751 or P0753.
• No shift solenoid 2-3 DTCs P0756 or P0758.
• No DTC P1810.
• Gear range is D4.
• Throttle angle between 12% and 70%. Engine torque
between 60 and 280 ft/lbs.
• Fluid temperature is between -10°C and 130°C
(14° F and 266° F).
• Engine speed is between 1200 and 3750 rpm. Input
speed is between 40 and 205 rpm.
• Slip between +140 and +500 rpm is detected.
• Shift Solenoid performance counters are clear.
Action Taken When DTC Sets
• PCM will command maximum line pressure.
• PCM will inhibit converter clutch engagement.
• PCM inhibits 4th gear if in hot mode.
• PCM will freeze shift adapts. PCM illuminates the
warning lamp.
Conditions For Clearing DTC
• For California vehicles, the PCM will turn the lamp off
after three consecutive ignition cycles without a failure
reported.
• The DTC can be cleared using the scan tool. The DTC
will be cleared when the vehicle has achieved 40 warm-
up cycles without a failure reported.
• The PCM will cancel the DTC default actions when the
fault no longer exists and the ignition is cycled “off”
long enough to power down the PCM.
Diagnostic Aids
• A pressure switch malfunction could set DTC P1870.
• A mechanical failure of the shift solenoids, or converter
clutch solenoid could set a DTC P1870.
• Internal transmission failures may result in a DTC
P1870.
• If any engine DTCs or TPS codes are present diagnose
and clear these DTCs first. Then check to see if the
transmission DTCs have reset.
Test Description
The numbers below refer to the step numbers on the diagnostic
chart.
1. This test checks the indicated range signal to the ac-
tual selected range. A faulty switch could set a DTC
P1870.
2. This test checks the torque converter for slippage
while in a commanded lock-up state.
Range
Gear
1-2 Sol
2-3 Sol
Fourth
Clutch
Overrun
Clutch
O/D
Roller
Clutch
FWD
Clutch
Direct
Clutch
Front
Band
Interm.
Sprag
Clutch
Interm.
Clutch
Lo
Roller
Clutch
Rear
Band
Overdrive
1st
On
Off
Ð
Ð
H
A
Ð
Ð
*
Ð
H
Ð
2nd
Off
Off
Ð
Ð
H
A
Ð
Ð
H
A
O
Ð
3rd
Off
On
Ð
Ð
H
A
A
Ð
O
A
O
Ð
4th
On
On
A
Ð
O
A
A
Ð
O
A
O
Ð
A = Applied
H = Holding
* = Holding but not effective
O = Overrunning
___________________________________________
Transmission/Transfer Case 5-117
®
05745159
DTC P1870 Transmission Component Slip
Step
Action
Value
Yes
No
1
Was the Powertrain On-Board Diagnostic (OBD) Sys-
tem Check performed?
—
Go to Step 2
Go to Power-
train OBD
System Check
2
Perform the Transmission Fluid Checking Procedure.
Refer to Line Pressure Check Procedure.
Did you perform the procedure?
—
Go to Step 3
Go to Trans-
mission Fluid
Checking Pro-
cedure
3
1.
Install the scan tool (Tech 2).
2.
With the engine OFF, turn the ignition switch to
the RUN position.
Important:
Before clearing the DTCs, use the scan
tool in order to record the Freeze Frame and Failure
Records for reference. The Clear Info function will
erase the data.
3.
Record the DTC Freeze Frame and Failure
Records.
4.
With the engine idling and at normal operating
temperature, apply the brake pedal.
5.
Select each transmission range: D1, D2, D3, D4,
N, R and P.
Does each selected transmission range match the scan
tool TFP Switch A/B/C display? (Refer to the Range
Signal table.)
—
Go to Step 4
Go to DTC
P1810 Pres-
sure Switch
Assembly
Malfunction
4
1.
Connect the J–21867 Pressure Gauge to the trans-
mission line pressure tap.
2.
Perform the Line Pressure Check.
3.
Refer to Line Pressure Check Procedure.
4.
Is the line pressure within specifications?
—
Go to Step 5
Go to the
applicable
System Diag-
nosis Table:
Low Line
Pressure
High Line
Pressure
5
Drive the vehicle under the following conditions:
• The transmission is in D4.
• The TCC is engaged.
• The APP angle is 12-70%.
At any time is the TCC Slip Speed within the specified
range for 1 second?
140-500 RPM
Go to Step 6
Go to Diag-
nostic Aids
6
Drive the vehicle under the following conditions:
• The transmission is in D3.
• Command the TCC ON with the scan tool.
• The APP angle is 12-70%.
At any time is the TCC Slip Speed within the specified
range for 6 seconds?
140-500 RPM
Go to Step 8
Go to Step 7
5-118
Transmission/Transfer Case
___________________________________________
®
7
Repeat the procedure in step 5. Drive the vehicle under
the following conditions:
• The transmission is in D4.
• The TCC is engaged.
• The APP angle is 12-70%.
Are the results the same as in step 5?
140-500 RPM
Go to Step 9
Go to Step 11
8
Refer to 4L80-E System Diagnosis Table, Slipping
TCC.
Did you find and correct the problem?
—
Go to Step 12
—
9
1.
Remove the transmission oil pan. Refer to Trans-
mission Oil Pan Removal in 4L80-E On-Vehicle
Service.
2.
Inspect for contaminated fluid and excessive mate-
rial in the pan.
Is the fluid or the pan contaminated?
—
Go to 4L80-E
Unit Repair
Go to Step 10
10
1.
Inspect the 1-2 SS Valve for contamination or dam-
aged seals.
2.
Inspect the 2-3 SS Valve for contamination or dam-
aged seals.
Did you find a problem?
—
Go to Step 12
Go to Step 11
11
Inspect the following components for contamination or
sticking:
• The 1-2 shift valve.
• The 2-3 shift valve.
• The 3-4 shift valve.
Did you find a problem?
—
Go to Step 12
Go to 4L80-E
Unit Repair
12
In order to verify your repair, perform the following
procedure:
1.
Select DTC.
2.
Select Clear Info.
3.
Operate the vehicle under the following condi-
tions:
• Drive the vehicle in 4th gear, with the TCC com-
manded ON.
• The APP Angle is 12-70%.
• The PCM must see a slip of -25 to +30 RPM for
greater than 1 second.
4.
Select Specific DTC. Enter DTC P1870.
Has the test run and passed?
—
System OK
Begin the
diagnosis
again. Go to
Step 1.
DTC P1870 Transmission Component Slip (Cont’d)
Step
Action
Value
Yes
No
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