OBD Guide
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P1704

Transmission Control Module

P1704 is an OBD-II diagnostic trouble code meaning: Transmission Control Module. Common causes: tcm module malfunction, damaged tcm wiring harness. Estimated repair cost: $56–278.

Severity
🔴 High
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–278 (est.)

Symptoms

  • Incorrect gear shifting
  • The gearbox goes into emergency mode
  • Check Engine light comes on
  • Loss of engine power
  • Difficulties when shifting gears

Causes

  • TCM module malfunction
  • Damaged TCM wiring harness
  • Poor contact in TCM connectors
  • Problems with module power or grounding
  • Software glitch in TCM

How to Fix

  1. Check the condition of the TCM wiring harness and connectors
  2. Check power supply and grounding of the module
  3. Scan the TCM for errors
  4. If necessary, reflash or replace the TCM
  5. Check the operation of the transmission after repair

Related codes

P1705P1706P1707

Error P1704 by Vehicle Brand

FordLincolnMercurySubaruVolkswagen

FAQ

What does the P1704 code mean?

P1704 is an OBD-II diagnostic trouble code that indicates: Transmission Control Module

What causes a P1704 error code?

The most common causes of P1704 include: TCM module malfunction; Damaged TCM wiring harness; Poor contact in TCM connectors; Problems with module power or grounding.

How do I fix a P1704 diagnostic trouble code?

To fix P1704: Check the condition of the TCM wiring harness and connectors. Check power supply and grounding of the module. Scan the TCM for errors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1704?

Limited driving only, diagnose soon

How much does it cost to fix P1704?

The estimated repair cost for P1704 is $56–278. Actual cost depends on your vehicle, location, and labor rates.

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