Hummer H1 Service Manual page 1186

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DTC P1656 Wastegate Solenoid Control Circuit
Step
1 Important: Before clearing DTCs use the scan tool Capture Info
Was the Powertrain On-Board Diagnostic (OBD) System Check perfom-
med?
2 1. Scan tool connected.
2. Ignition ON, engine OFF.
3. With scan tool, command Boost solenoid ON and OFF and listen for an
audible click.
Does the solenoid turn ON and OFF (audible click) with each command?
3 1. Ignition OFF.
2. Disconnect the PCM connector containing the Boost solenoid control
circuit.
3. Ignition ON.
4. Using DVM J–39200 on 10 Amp scale, measure current from the sole-
noid control circuit in the PCM harness connector to ground for 2 min-
utes.
Is current draw less then the specified value, but not zero?.
4 1. Ignition OFF.
2. PCM connector still disconnected.
3. Disconnect Boost solenoid.
4. Using DVM J–39200, measure resistance from the solenoid control cir-
cuit in the PCM harness connector to ground.
Does DVM display infinite resistance?
5 1. Disconnect Boost solenoid.
2. Ignition ON, engine OFF.
3. Connect a test light between the terminals at the harness connector.
4. Using a scan tool. command the solenoid ON and OFF.
Does test light turn ON and OFF with each command?
6 1. Ignition ON engine OFF.
2. With a test light connected to ground, probe the ignition feed circuit at
the Boost solenoid harness connector.
Is the test light ON?
7 1. Ignition OFF.
2. Reconnect solenoid.
3. Disconnect the PCM harness containing the solenoid control circuit.
4. Ignition ON.
5. With a fused jumper wire connected to ground, probe the solenoid con-
trol circuit in the PCM hamess connector.
Does the solenoid operate (audible click)?
8 DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic
Aids. If additional DTCs were stored refer to the applicable DTC table(s)
first.
Are any additional DTCs stored?
05745159
Action
PCM/Tech 1 Scan Tool 121
Value(s) Yes
— Go to Step 2.
— Go to Step 3.
0.75A Go to Step 8.
— Go to Step
13.
— Go to Step 9.
— Go to Step 7. Go to Step 12.
— Go to Step
11.
— Go to the
applicable
DTC table
No
Go to OBD
System Check.
Go to Step 5.
Go to Step 4.
Go to Step 10.
Go to Step 6.
Go to Step 10
Go to Diag-
nostic Aids