Which part do I need to fix P1823

2001 CADILLAC DEVILLE
126,000 MILES
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PHATBOY76
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  • 2 POSTS
Hi,

My 2001 Cadillac Deville failed inspection in Massachusetts and the code was P1823. Which part will I need to fix this problem please? Thanks!
Sep 4, 2012 at 9:03 PM
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KHLOW2008
  • ✓ASE Certified Mechanic
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This is a fault with the transmission Internal Mode switch and testings have to be carried out to determine if the switch, its wiring or the PCM.

A scan tool would be helpful to perform diagnostics.
Sep 4, 2012 at 9:22 PM
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PHATBOY76
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Thanks so much for your response! The trouble code I am getting is"P1823 Internal Mode Switch Circuit P Low". Do you know what kind of scan tool will I need and where could I get one? Will this help me to figure out definitively if it's just the wiring, the switch, or the PCM? Could this be the PNP? Thanks again!
Oct 18, 2012 at 11:29 PM
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KHLOW2008
  • ✓ASE Certified Mechanic
  • 41,814 POSTS
  • ASE Certified Mechanic
A scan tool capable of performaing actuation test is required and there are many different suppliers which you would have no problem locating if you google.

For wirings you might need more than the scan tool, a DVOM is more practical.

Problem can be any of the following only.
PCM
Internal Mode Switch (located within transmission)
Transaxle wire harness

Oct 19, 2012 at 5:07 PM
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