1991 Chevy Blazer Check Engine Light

GMC
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CMS
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i have a 1991 chevy blazer 4 wheel drive 128000 miles my check engine light keeps coming on and off i cant afford a scanning kit and auto stores cant test it because it a 91 please help as soon as possible
Feb 20, 2006 at 4:14 AM
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MVANNESSJR
  • ✓Experienced Mechanic
  • 223 POSTS
Well, they don't need to scan it, but you can get the local auto shop to read the codes. If you want to do it yourself use the old paper clip method.

Jumper the A and B pins of the 12 pin ALDL OBD1 connector with a paper clip located under the driver stearing column. While the car is off, sitting still, turn the ignition key forward while this jumper is in place. Do not start the car. The Service Engine Soon ( SES ) light will flash in a repeating sequence, telling which trouble codes have been set in the ECM.
Feb 20, 2006 at 6:19 PM
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Suggested Repair

Have a shop read the stored codes, or retrieve them with the paper-clip method: jumper pins A and B of the 12-pin ALDL OBD1 connector under the steering column, turn the key on without starting, and read the repeating Service Engine Soon flash codes.

Conversation Summary

The owner of a 1991 Chevy Blazer 4x4 with 128,000 miles says the check engine light comes on and off and cannot get a scan because it is a 1991. The expert says a shop can read the codes without a modern scanner, or the owner can jumper ALDL pins A and B and read the ECM trouble codes from the flashing SES light.

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