Mechanics

CHEVY S-10 4HI AND 4LO LIGHTS BOTH FLASH AND GO BACK TO 2HI, CHECKED TCCM FOR CORRODED WIRES, CHECKED FOR VACUM LEAKS, UNHOOKED THE BATTERY TO RESET THE TCCM, REPLACED SWITCH ON THE DASH, THIS YEAR HAS NO VACUM SWITCH ON THE FIRE WALL, CHECKED

2003 Chevrolet Blazer • 126,000 miles

2003 chevy blazer, 4hi and 4lo lights both flash and go back to 2hi. Only in neutral do I get a response from the switch in drive it does nothing. It will go into 4lo just fine. Checked the tccm for bad connection and corroded wires cleaned reassembled and unooked the battery to reset the tccm and still nothing? No visible vacum leaks, actuator under the battery has no leaks, I did notice with the vehicle running there is no vacum coming out or going in from the vacum line that goes to the actuator under the battery. Im at a loss! There is no vacum switch on the firewall like some other models I have read about. I also changed the 3 switch panel on the dash and still nothing. HELP!
Avatar
Tonycr250
April 15, 2012.



Check your fuses first, underhood as well as ip. Then check the ground on the right side of dash for being loose. It may be your encoder motor on the t-case though. Your vacuum actuator switch on tcase cold be not working or havea line disconnected as well.

Hmac300
Apr 15, 2012.
Sorry I forgot to mention before I did check the fuses, I tried to get to the actuator on tran case but its such a tight space its hard to access. I will check the ground though that I havent done.I was kind of leading towards the encoder motor also. Thanks for the tips.

Tiny
Tonycr250
Apr 15, 2012.