Cadillac P1838: Internal Mode Switch A Circuit High Voltage

Is your scanner showing Cadillac P1838?
No worries. We'll show you what it means and how to deal with it.

Presented by

Randy Worner

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Cadillac P1838: Internal Mode Switch A Circuit High Voltage

OVERVIEW

Severity

High

DIY Difficulty Level

Intermediate

Repair Cost

$170-$300

Can I Still Drive?

Yes

What Does The Cadillac P1838 Code Mean?

No OSS DTCs P0722 or P077B. The system voltage is 11-18 V. The engine run time is greater than 5 seconds. The system voltage is 11-18 V. The vehicle speed is less than 200 km/h (124 mph) for 5 seconds.

What Are The Potential Causes Of The Cadillac P1838 Code?

Any one or more of the following conditions:
The IMS signal circuit A, B, or P are Low in Park for greater than 8 seconds.
The IMS signal circuit A is Low in D for 8 seconds.
The IMS signal circuit C is High in D for 8 seconds.
The TCM detects an invalid range from the IMS for 3.25 seconds.
The IMS signal circuit C is high in D for greater than 8 seconds.
Park/Neutral Switch equals P/N and the IMS state is not Park or Neutral, or the Park/Neutral switch is not Park or Neutral and the IMS state equals Park or Neutral for 4 seconds.
Or the automatic transmission manual shift shaft position switch assembly indicates a transitional state for 8 seconds.