Preheating on Diesel engine improves cold starting with glow plug which heat combustion chamber. Preheating before starting improves cold starting, preheating after starting reduces to generate white smog. GCU(Glow plug Control Unit) is installed on the upper side of timing chain cover and is operated by 12V power supply. GCU receives sensors data such as 1)engine coolant temperature, 2)engine rpm, 3)fuel injection amount from ECM via CAN communication in order to control glow plug. GCU controls 1)glow plug operation with PWM, 2)compensates voltage when low voltage 3)controls not to flow over current on glow plug 4) retrieves DTC after diagnosing each glow plug corresponding to engine condition.

ISS(Instant Starting System) operated by 4.4Valtage, which is slim and enhanced heating performance, is newly adopted on S engine. GCU emerges battery voltage to glow plug directly for 1~ 2sec. at IG key ON. After that, GCU controls glow plug operating voltage with PWM corresponding to Engine condition. ISS glow plug is increased to 1000℃ within 2 ~3sec. so that starting performance is reached as same level as gasoline. In addition, it is realized that consumption of electricity is optimized by PWM control.

DTC P0670 is set if power supply is not supplied to main power circuit on GCU under IG ON condition. This DTC is retrieved when main power of GCU is short to battery/ground, open or faulty GCU.

【Preheating time at starting】Over 45 RPM , Maximum for 30sec under -80 ℃ condition.

Fig.1) Signal waveform of glow plug before and after starting at 30℃ engine coolant temperature with IG key operation.(IG key OFF to Cranking)

Fig. 2) Signal waveform of glow plug at Idle status.

☞ 1~ 2sec. after IG key ON, operating duty for glow plug reaches approx. 100%. After that, PWM is controlled corresponding engine condition.(Approx. 30 ~ 32Hz)