1994 GMC Sierra SES Light and Harsh Shift

GMC SIERRA
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DAVY916
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I have a 1994 GMC sierra ext cab 1/2 ton pickup with 170,000 miles on it. I have the problem of my service engine soon light coming on sometimes and my trans. shifts like I'm at the drag strip. I ran a diagnostic and its something to do with fuel seneor set too low and 32 ERG system trouble. I have already changed the ERG sensor and that hasn't fixed the problem. Any ideas of what the problem could be?
Jan 14, 2007 at 10:36 PM
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SERVICE WRITER
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One code is 32? and the other?
Motor size?
Jan 15, 2007 at 2:33 AM
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DAVY916
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The motor is a 5.7 L and I'm not for sure what the other code was, but it kept saying that the fuel mixture was lean and then rich going back and forth.
Jan 15, 2007 at 3:20 AM
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SERVICE WRITER
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The troubleshooting charts points to egr valve, egr sensor or PCM quad driver. Before going into part replacement, check all the connectors for the above for abnormalities. There is a troubleshooting flow chart available through mitchell1 which is linked below if you want to go through the testing procedure. I would address this code first, in the event the pcm is bad and possiblily contributing to the the 2nd unknown code.
Jan 15, 2007 at 4:36 AM

Suggested Repair

Before replacing parts, inspect the connectors for the EGR valve, EGR sensor, and PCM quad driver for abnormalities. Address code 32 first using the Mitchell1 troubleshooting chart, since a faulty PCM may also contribute to the lean/rich fuel mixture code.

Conversation Summary

The owner of a 1994 GMC Sierra 5.7L reported an intermittent service engine soon light and harsh transmission shifts. Diagnostics indicated a low fuel sensor reading and code 32 EGR trouble; replacing the EGR sensor did not fix it. The expert advised checking the EGR valve, EGR sensor, and PCM quad driver connectors and addressing code 32 first because a bad PCM could also affect the fuel mixture code.

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