P0670
Glow Plug Module Control Circuit More details
Powertrain Ignition System Glow Plug Control 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The glow plug control module isn't communicating properly with the engine computer, like a dimmer switch that's broken and won't respond to commands. This prevents the glow plugs from heating the engine cylinders before a cold start on diesel engines.

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Symptoms You May Notice
3 known symptoms for this code
Hard starting or no start in cold weather
Excessive white smoke from exhaust during cold starts
Check Engine Light illuminated
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage and current signals from the glow plug control module during the glow plug pre-heating cycle. It checks for proper circuit continuity and module response when commanding glow plugs on. If the module fails to acknowledge or draw expected current, the fault is logged.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Glow plug control module voltage 12-14V with proper response to command No voltage response or open/short circuit detected
Glow plug current draw 15-100A during pre-heat cycle Zero amps or excessive draw indicating circuit failure
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Battery and battery terminals
Clean corrosion from battery terminals and test battery voltage; low voltage can cause module communication failure.
2
Glow plug control module connector
Inspect and reseat the connector at the glow plug module for loose pins or corrosion causing poor electrical contact.
3
Glow plug control module
Replace the module if connector and wiring test good but fault persists.