AutoCodes – Mercury – P1793 Mercury

P1793 Mercury Code - Ignition Supply Malfunction

Quick Answer

The Powertrain Control Module (PCM) monitors the Ignition Switch Position Run (ISP-R) circuit. Common causes include Faulty Ignition Switch Position Run (ISP-R), ISP-R harness is open or shorted, ISP-R circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1793 Mercury indicates Ignition Supply Malfunction.
Common causes: Common causes include Faulty Ignition Switch Position Run (ISP-R), ISP-R harness is open or shorted, ISP-R circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,583

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 19, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1793 Mercury Description

The Powertrain Control Module (PCM) monitors the Ignition Switch Position Run (ISP-R) circuit. This DTC sets if the voltage drops below 7 volts or rises above 16 volts.

OBDII Code P1793 Mercury - Ignition Supply Malfunction - AutoCodes.com — P1793 Mercury Code - Ignition Supply Malfunction

What does this mean?

What are the Possible Causes of the DTC P1793 Mercury?

Faulty Ignition Switch Position Run (ISP-R)
ISP-R harness is open or shorted
ISP-R circuit poor electrical connection
Low battery charge

How to Fix the DTC P1793 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1793 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.