DIESEL CONTROL SYSTEM
DTC P0820 NEUTRAL S/W MALFUNCTION
Neutral Gear Switch is installed in M/T vehicle and senses driver’s intension to shift gear(driver’s intension to drive).ECM
recognizes engaged gear based on vehicle speed sensor signal and engine RPM in M/T vehicle. And Black Smoke limiting
fuel quantity value varies according to engaged gear.(As higher gear shift is engaged, maximum possible fuel injection
quantity increases to raise power generation.)The recognition of engaged gear is available when vehicle speed reachs to
2Km/h - the minimum speed for ECM to detect. When vehicle starts to move after standing for a while and vehicle speed
does not reach to 2Km/h, fuel quantity mapping value at neutral gear is adopted to vehicle. Moreover, this phenomenon
is more serious when vehicle requires high power generation such as the situation when vehicle is on the slope. To cope
with this problem, neutral gear switch which senses driver’s intension of starting to move is applied. And fuel injection
quantity mapping value suitable for 1st gear is adopted immediately.
To reduce black smoke produced during rapid acceleration when no load is applied, fuel injection quantity at none
load condition is 70% of that at 1st gear.
P0820 is set when 1)gear is engaged at non-neutral positon at engine ON, but clutch signal is not detected. or 2)only
neutral signal is detected at above 600RPM or above 80Km/h. for more than 3 sec.. This code is due to open, short to
battery or ground in neutral gear switch circuit.
DTC DETECTING CONDITION
• Signal monitoring
• During driving
• Short to Battery
• short to GND, wiring open
• Nertral gear switch
• Nertral gear switch circuit
Except Neutral Position