Hummer H1 Service Manual page 320

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Step
9 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:
• Key ON, the engine is running.
• Drive the vehicle in 1st, 2nd, 3rd and 4th gear.
• The PCM must see a valid gear change versus the
comanded gear for 10 seconds.
4. Select Specific DTC. Enter DTC P1871.
Has the test run and passed?
05745159
DTC P1871 Undefined Gear Ratio (Cont'd)
Action
Transmission/Transfer Case
Value
System OK
5-121
Yes No
Begin the
Diagnosis
again.
Go to Step 1