Powertrain, generic · Computer and auxiliary outputs

P0683 Glow Plug Control Module 1 to PCM Communication Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Glow plug module 1 reports to the engine module over a feedback wire (Bosch-type systems expect it inverse to the activation line) or the bus; GM and Ford report a lost bus link as U0106, Saab as P0380/P1380, and no manufacturer document available to us uses P0683/P0684 themselves. P0683 means communication or feedback from the glow module to the engine module is missing or the line is open or shorted. The engine module then no longer receives plug status reports, so the individual plug monitoring fails; depending on design the glow module keeps glowing on its own timing or not at all. The activation line in the other direction is P0670/P0383/P0384.

Likely causes

Communication or feedback wire between glow and engine module open, chafed or connector corroded
Glow module without supply or ground (fuse, main cable) – does not answer
Glow module faulty internally
Glow or engine module software or programming

Symptoms

  • Check engine light (glow plug lamp may flash or stay on)
  • Harder cold start, long cranking in frost
  • Rough running and white smoke after a cold start
  • No individual plug reports any more

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

glow plug control moduleglow plug feedback lineengine control module

Related codes

P0684P0670P064CP052FP06FCU0106

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com.