will not engage into 4x4 high range
Jul 3, 2009 at 12:08 AM
1992 GMC S15 4x4
1992 GMC S15
CARL HOLLY
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Could be the switch, the front axle actuator, the transfer case encoder motor, the vacuum switch on the transfer case, bad front differential. You need to do a bit of troubleshooting to find out what.
First jack up ONE front tire. Then with the engine idling and 2WD selected try to rotate the tire by hand. It should rotate easily. Now switch to 4X4 and see if it will still turn. If it does look at the front drive shaft. Is it turning when you move the tire? If it is then the problem is probably in the transfer case. If it isn't then try this test. Open the hood and apply vacuum to the front axle actuator. Now try the test again. If it won't rotate now then the problem is the vacuum control line from the engine. The usual item is the vacuum switch on the transfer case.
First jack up ONE front tire. Then with the engine idling and 2WD selected try to rotate the tire by hand. It should rotate easily. Now switch to 4X4 and see if it will still turn. If it does look at the front drive shaft. Is it turning when you move the tire? If it is then the problem is probably in the transfer case. If it isn't then try this test. Open the hood and apply vacuum to the front axle actuator. Now try the test again. If it won't rotate now then the problem is the vacuum control line from the engine. The usual item is the vacuum switch on the transfer case.
Dec 6, 2009 at 7:24 PM