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Home / DTC / P1702 — A/T warning lamp connector fault

P1702 — A/T warning lamp connector fault

Detailed page for trouble code P1702.

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Code

P1702

ALFA ROMEO P — Powertrain

A/T warning lamp connector fault

Brand: ALFA ROMEO
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or corroded A/T warning lamp connector pins
  • Broken, chafed or disconnected wiring in the lamp circuit
  • Poor or missing ground for the lamp circuit
  • Water ingress or contamination inside the connector
  • Loose connector or improperly seated mating halves
  • Faulty instrument cluster (lamp/driver) or transmission control module (TCM) connector

Symptoms

  • A/T warning lamp illuminated or flashing on instrument cluster
  • Intermittent illumination of A/T warning lamp (comes and goes with vibration)
  • Possible related transmission fault indications or limp mode (if communication/signals affected)
  • No other engine/transmission faults but lamp remains on after clear

What to check

  • Read and record freeze frame and related codes with a scan tool; note if code is stored as current or historic
  • Visually inspect A/T warning lamp connector(s) at instrument cluster and TCM for corrosion, bent pins, water or damage
  • Inspect wiring harness routing for chafing, pinching, or previous repairs near bulkhead and transmission
  • Wiggle test connectors and harness while watching lamp or live data to reproduce fault
  • Check for proper connector seating and retention clips
  • Verify related ground points at cluster and chassis are clean and tight

Signal parameters

  • Connector pin voltages with ignition ON: battery voltage (approx. 12V) on feed circuit
  • Lamp drive/return circuit continuity between instrument cluster and TCM/ground (ohms)
  • Ground resistance from lamp circuit ground to chassis (
  • Look for intermittent open/short to ground or battery when harness is moved (voltage fluctuation)
  • Scan-tool lamp status/ECU reports (on/off, lamp commanded)

Diagnostic algorithm

  1. Confirm P1702 and any related codes with a scan tool; note occurrence conditions and freeze-frame data.
  2. Visually inspect the instrument cluster connector, TCM connector and related harness sections for damage, corrosion or signs of water ingress; repair any visible damage.
  3. With ignition OFF, disconnect connectors and inspect pins for corrosion, compression, or pushed-out terminals. Repair/replace connectors or pins as required.
  4. Backprobe the lamp circuit with ignition ON: verify feed voltage and ground presence. Compare to expected battery voltage and verify lamp driver signal behavior when lamp is commanded.
  5. Perform continuity check from the instrument cluster lamp pin to the TCM/connector pin and to ground; repair any open or high-resistance circuits.
  6. Perform a wiggle test on the harness/connectors while monitoring lamp status or live data to identify intermittent faults.
  7. Clean and apply dielectric grease to clean connectors; reseal or replace housings affected by water ingress.
  8. After repairs, clear codes, cycle ignition and road test under conditions that produced the fault to confirm the issue is resolved.
  9. If wiring and connectors test good but fault persists, test/replace instrument cluster or TCM following manufacturer procedures and module programming requirements.

Likely causes

  • Corrosion or water in the lamp connector at the bulkhead/front harness
  • Loose or pushed-out pin in the cluster or TCM connector
  • Wire abrasion where harness passes through bulkhead or near engine/transmission
  • Poor ground at instrument cluster or chassis ground point

Fault status

⚠️ Status
A/T warning lamp connector circuit fault detected — open/short/intermittent connection between lamp, instrument cluster and transmission control circuits.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0700 P0705 P0720 P0722 P1701
89

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