Brake warning light flashing

1990 GMC VAN
77,000 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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STOCK0823
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  • 1 POST
Brake light in dash flashes a code 6, which according to chart, is a bad speed sensor. My van is a g3500, 350 v8, 400 turbo transmission. I do not know where speed sensor is located. Can you help?
Oct 21, 2018 at 6:33 PM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,193 POSTS
  • ASE Certified Mechanic
Hi and thanks for using 2CarPros.com.

The code indicates an erratic signal in the speed signal. It could be a bad sensor, partially disconnected sensor, or damaged wiring/connector/corrosion. I attached two pictures for you. The first one indicates the location of the sensor (left side of transmission). The second is a diagnostic flow chart.

Let me know if you have other questions or need additional information. Also, ignore picture 2. For some reason I cannot delete it.

Take care,
Joe
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Oct 21, 2018 at 7:29 PM
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STOCK0823
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Thanks a lot. I now know location of sensor. I will check it out Tuesday. Again, thank you very much and I will use 2carpros again.
Oct 23, 2018 at 10:14 AM
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