INTRODUCTION
Note. The following figures are courtesy of General Motors Corp.
Pin voltage charts are supplied (when available) to reduce diagnostic time. Checking pin voltages at the electronic control unit determines whether it is receiving and transmitting proper signals. Charts may also help determine if control unit harness is shorted or open.
Note. Unless stated otherwise in testing procedures, perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.
4.3L, 5.0L & 5.7L WITH 4L60-E A/T
Note. This PCM voltage chart, along with digital voltmeter, can help save diagnosis time. Voltage readings may vary slightly depending on battery voltage and alternator output.
The following conditions must be met before testing
- Engine at operating temperature.
- Engine in closed loop operation.
- Engine idling (Engine Operating column).
- DLC test terminal NOT grounded.
- Scan tester NOT installed.
PCM Terminal Identification & Pin Voltages (1 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 1
VCM Terminal A-B Connector - Red (1 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 2
PCM Terminal Identification & Pin Voltages (2 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 3
VCM Terminal A-B Connector - Red (2 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 4
PCM Terminal Identification & Pin Voltages (3 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 5
VCM Terminal E-F Connector - Blue (3 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 6
PCM Terminal Identification & Pin Voltages (4 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 7
VCM Terminal E-F Connector - Blue (4 Of 4) ("C" & "K" Series 4.3L, 5.0L & 5.7L With 4L60-E A/T). Scheme 8
4.3L, 5.0L, 5.7L & 7.4L WITH 4L80-E A/T
Note. This PCM voltage chart, along with digital voltmeter, can help save diagnosis time. Voltage readings may vary slightly depending on battery voltage and alternator output.
The following conditions must be met before testing
- Engine at operating temperature.
- Engine in closed loop operation.
- Engine idling (Engine Operating column).
- DLC test terminal NOT grounded.
- Scan tester NOT installed.
PCM Terminal Identification & Pin Voltages (1 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 9
PCM Terminal A-B Connector - Red (1 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 10
PCM Terminal Identification & Pin Voltages (2 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 11
PCM Terminal A-B Connector - Red (2 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 12
PCM Terminal Identification & Pin Voltages (3 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 13
PCM Terminal E-F Connector - Blue (3 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 14
PCM Terminal Identification & Pin Voltages (4 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 15
PCM Terminal E-F Connector - Blue (4 Of 4) ("C", "K" & "P" Series 4.3L, 5.7L & 7.4L With 4L80-E A/T). Scheme 16
4.3L & 7.4L WITH M/T
Note. This PCM voltage chart, along with digital voltmeter, can help save diagnosis time. Voltage readings may vary slightly depending on battery voltage and alternator output.
The following conditions must be met before testing
- Engine at operating temperature.
- Engine in closed loop operation.
- Engine idling (Engine Operating column).
- DLC test terminal NOT grounded.
- Scan tester NOT installed.
PCM Terminal Identification & Pin Voltages (1 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 17
PCM Terminal A-B Connector - Red (1 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 18
PCM Terminal Identification & Pin Voltages (2 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 19
PCM Terminal A-B Connector - Red (2 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 20
PCM Terminal Identification & Pin Voltages (3 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 21
PCM Terminal E-F Connector - Blue (3 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 22
PCM Terminal Identification & Pin Voltages (4 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 23
PCM Terminal E-F Connector - Blue (4 Of 4) ("C" & "K" Series 4.3L & 7.4L With M/T). Scheme 24
5.0L & 5.7L WITH M/T
Note. This ECM voltage chart, along with digital voltmeter, can help save diagnosis time. Voltage readings may vary slightly depending on battery voltage and alternator output.
The following conditions must be met before testing
- Engine at operating temperature.
- Engine in closed loop operation.
- Engine idling (Engine Operating column).
- DLC test terminal NOT grounded.
- Scan tester NOT installed.
ECM Terminal Identification & Pin Voltages (1 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 25
ECM Terminal A-B Connector (1 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 26
ECM Terminal Identification & Pin Voltages (2 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 27
ECM Terminal A-B Connector (2 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 28
ECM Terminal Identification & Pin Voltages (3 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 29
ECM Terminal C-D Connector (3 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 30
ECM Terminal Identification & Pin Voltages (4 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 31
ECM Terminal C-D Connector (4 Of 4) ("C" & "K" Series 5.0L & 5.7L With M/T). Scheme 32
ALL 6.5L DIESEL
Note. This PCM voltage chart, along with digital voltmeter, can help save diagnosis time. Voltage readings may vary slightly depending on battery voltage and alternator output.
The following conditions must be met before testing
- Engine at operating temperature.
- Engine in closed loop operation.
- Engine idling (Engine Operating column).
- DLC test terminal NOT grounded.
- Scan tester NOT installed.
