Circuit/System Testing

WARNING: This page is about a different car, the 2008 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect the MGU X2 and the SGCM X2 connectors. Refer to Generator with Starter Replacement and Generator Control Module Replacement .
Test the circuits in the SGCM to MGU Terminal Reference Table as indicated below. Also test these circuits for short to ground.
- If any of the circuits are not within specification, check for an open/high resistance or short to ground.
Reconnect SGCM connector X2.
Test the circuits in the MGU to SGCM Specification Table to ground as indicated below.
- If any of the circuits are not within the specified range, replace the SGCM.
Reconnect the MGU X2 connector and disconnect the SGCM X2 connector. Refer to Generator with Starter Replacement and Generator Control Module Replacement .
Test the circuits in the SGCM to MGU Specification Table as indicated below.
- If all circuits test normal, replace the MGU.

SGCM to MGU Terminal Reference Table

MGU Connector/Terminal	SCGM Connector/Terminal	Minimum Resistance	Maximum Resistance
Harness Continuity Test
B	X2/7	-	less than 1 ohm
C	X2/6	-	less than 1 ohm
D	X2/4	-	less than 1 ohm
E	X2/17	-	less than 1 ohm
F	X2/20	-	less than 1 ohm
G	X2/19	-	less than 1 ohm
H	X2/5	-	less than 1 ohm

MGU to SGCM Specification Table

MGU Connector/Terminal	Signal Name	Minimum Resistance	Maximum Resistance
Measurements made to ground. SGCM connected and MGU disconnected.
D	REZ-	1.6k ohms	2k ohms
H	REZ+	1.6k ohms	2k ohms
C	REZ3	Over 1 M ohm	-
B	REZ4	Over 1 M ohm	-
E	REZGS (GND)	-	less than 5 ohm
G	REZ1	Over 1 M ohm	-
F	X2/5	Over 1 M ohm	-

SGCM to MGU Specification Table

SGCM Connector/Terminal	SGCM Connector/Terminal	Minimum Resistance	Maximum Resistance
MGU connected and SGCM disconnected.
X2/4	X2/5	20.1 ohms	26.7 ohms
X2/6	X2/19	32.4 ohms	43.0 ohms
X2/7	X2/20	32.9 ohms	43.5 ohms
X2/4	X2/6	Over 1 meg ohm	-
X2/4	X2/7	Over 1 meg ohm	-
X2/6	X2/7	Over 1 meg ohm	-