LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Honda >> 2021 >> Ridgeline RTL-E >> Repair and Diagnosis (Single Page) >> Quick Lookups >> Electrical Component Locations >> Electrical System - Testing & Troubleshooting >> Connector View >> Under-Dash Fuse/Relay Box Connector for Inputs and Outputs (2017 2018 2019)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Under-Dash Fuse/Relay Box Connector for Inputs and Outputs (2017 2018 2019)

Connector Index
UNDER-DASH FUSE/RELAY BOX CONNECTOR D (44P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR E (36P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR F (18P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR G (4P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR H (13P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR M (12P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR N (20P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR P (24P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR Q (10P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR R (16P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR S (18P)
UNDER-DASH FUSE/RELAY BOX CONNECTOR T (10P)

UNDER-DASH FUSE/RELAY BOX CONNECTOR D (44P) (female terminals) 

GHH451830Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 --- Not used ---
2 --- Not used ---
3 --- Not used ---

*1: With back power window

*2: With power seat

*3: With front seat heater and without ventilated seat

*4: With power lumbar support

*5: With driving position memory or with rear seat heater

*6: With AC power outlet

Terminal number Terminal name Description Signal
4* 1 +B P/W BACK +B power supply About battery voltage at all times
5 +B FUEL PUMP +B power supply About battery voltage at all times
6 --- Not used ---
7* 2 +B DR P/SEAT(REC) +B power supply About battery voltage at all times
8 BACK LT Output back-up lights signal With vehicle in ON mode and R position/mode: about battery voltage
If none of above conditions are met: less than 0.2 V
9* 2 +B DR P/SEAT(SLI) +B power supply About battery voltage at all times
10 +B RR L P/W Drives left rear power window motor With vehicle in ON mode: about battery voltage
11 L SIDE DOOR LOCK Drives left rear door lock actuator When left rear door lock actuator in locking operation: about battery voltage
12 L SIDE DOOR UNLOCK Drives left rear door lock actuator When left rear door lock actuator in unlocking operation: about battery voltage
13* 3 +B H/SEAT +B power supply About battery voltage at all times
14 GND MICU ground Less than 0.2 V at all times
15 --- Not used ---
16 --- Not used ---
17 TRUNK ACT Drives in-bed trunk lid release actuator When in-bed trunk lid release actuator in open operation: about battery voltage
18 +B RR R P/W Drives right rear power window motor With vehicle in ON mode: about battery voltage
19* 4 +B DR POWER LUMBAR +B power supply About battery voltage at all times
20 --- Not used ---
21 --- Not used ---
22 --- Not used ---
23 --- Not used ---
24 --- Not used ---
25 RR DR SILCON UNLOCK Detects left rear door lock knob switch (UNLOCK) signal With left rear door lock knob switch UNLOCK: less than 0.2 V
With left rear door lock knob switch LOCK: about battery voltage
26 RR AS SILCON UNLOCK Detects right rear door lock knob switch (UNLOCK) signal With right rear door lock knob switch UNLOCK: less than 0.2 V
With right rear door lock knob switch LOCK: about battery voltage
27 --- Not used ---
28 RR DOOR SW Detects right rear door switch signal With right rear door switch ON: less than 0.2 V
With right rear door switch OFF and MICU is wake-up mode: about battery voltage
With right rear door switch OFF and MICU is sleep mode: pulse
29 --- Not used ---
30 --- Not used ---
31* 5 IG1 METER IG1 power source With vehicle in ON or START mode: about battery voltage
32 L TURN SIG Output left rear turn signal light signal With left turn signal light ON: about battery voltage

*1: With back power window

*2: With power seat

*3: With front seat heater and without ventilated seat

*4: With power lumbar support

*5: With driving position memory or with rear seat heater

*6: With AC power outlet

Terminal number Terminal name Description Signal
33 R TURN SIG Output right rear turn signal light signal With right turn signal light ON: about battery voltage
34 RL DOOR SW Detects left rear door switch signal With left rear door switch ON: less than 0.2 V
With left rear door switch OFF and MICU is wake-up mode: about battery voltage
With left rear door switch OFF and MICU is sleep mode: pulse
35 FL DOOR SW Detects driver's door switch signal With driver's door switch ON: less than 0.2 V
With driver's door switch OFF and MICU is wake-up mode: about battery voltage
With driver's door switch OFF and MICU is sleep mode: pulse
36 --- Not used ---
37 FR DOOR SW Detects front passenger's door switch signal With front passenger's door switch ON: less than 0.2 V
With front passenger's door switch OFF and MICU is wake-up mode: about battery voltage
With front passenger's door switch OFF and MICU is sleep mode: pulse
38 --- Not used ---
39 BED GATE SW+ Detects tailgate switch signal With tailgate switch ON: less than 0.2 V
With tailgate switch OFF and MICU is wake-up mode: about battery volt
With tailgate switch OFF and MICU is sleep mode: pulse
40* 6 NSW Output NSW signal With vehicle in ON mode, P position/mode, and engine speed at least 500 rpm: less than 0.2 V
If none of above conditions are met: about 5 V
41 --- Not used ---
42 GND MICU ground Less than 0.2 V at all times
43 --- Not used ---
44 CARGO LT Detects cargo area light signal With cargo area light ON: about battery voltage

*1: With back power window

*2: With power seat

*3: With front seat heater and without ventilated seat

*4: With power lumbar support

*5: With driving position memory or with rear seat heater

*6: With AC power outlet

UNDER-DASH FUSE/RELAY BOX CONNECTOR E (36P) (female terminals) 

GHH451831Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 FR WASHER RLY CL- Drives windshield washer motor relay With front washer switch ON: less than 0.2 V
With front washer switch OFF: about battery voltage
2 --- Not used ---
3 --- Not used ---
4 +B HAZARD +B power supply About battery voltage at all times
5 --- Not used ---
6 --- Not used ---
7 STOP SW Detects brake pedal position switch signal With brake pedal pressed: about battery voltage
With brake pedal released: less than 0.2 V
8 L H/L HI Output left headlight (HI) signal With headlight (HI) is ON: about battery voltage
With headlight (HI) is OFF: less than 0.2 V
9 --- Not used ---
10 IG1 VB SOL IG1 power source With vehicle in ON or START mode: about battery voltage
11 +B ACC/IG2 MAIN IG2 power source With vehicle in ON mode: about battery voltage
12 IG1 FUEL PUMP IG1 power source With vehicle in ON or START mode: about battery voltage
13 --- Not used ---

*1: With LED daytime running light

*2: With front fog light

Terminal number Terminal name Description Signal
14 SMALL LT RLY OUT Output small lights signal With small lights are ON: about battery voltage
With small lights are OFF: less than 0.2 V
15 WIPER HI/LO RLY CL- Drives windshield wiper high/low relay With vehicle in ON mode and windshield wiper LO speed: less than 0.2 V
With vehicle in ON mode and windshield wiper HI speed: about battery voltage
16 WIPER INT RLY CL- Drives windshield wiper intermittent relay With vehicle in ON mode and windshield wiper operation: less than 0.2 V
With vehicle in ON mode and windshield wiper stopping: about battery voltage
17 ATP-R Detects transmission range switch (R) signal With vehicle in ON mode and R position/mode: less than 0.2 V
If none of above conditions are met: about battery voltage
18 --- Not used ---
19 --- Not used ---
20* 1 DRL SIG Output daytime running lights signal About 0 V-battery voltage (depending on daytime running light brightness)
21* 2 FR FOG LT RLY CL- Drives front fog light relay With front fog light switch ON: less than 0.2 V
With front fog light switch OFF: about battery voltage
22 --- Not used ---
23 --- Not used ---
24 H/L LO RLY CL- Drives headlight relay With headlight (Lo) is ON: less than 0.2 V
With headlight (Lo) is OFF: about battery voltage
25 SMALL LT RLY CL- Drives small light relay With small lights are ON: less than 0.2 V
With small lights are OFF: about battery voltage
26 IG1 VSA IG1 power source With vehicle in ON or START mode: about battery voltage
27 ATP-P Detects transmission range switch (P) signal With out of P position/mode and MICU is wake-up mode: about battery voltage
With P position/mode: less than 0.2 V
With out of P position/mode and MICU is sleep mode: pulse
28 FR WIPER AS Detects windshield wiper motor auto-stop position signal With windshield wiper at out of auto-stop position and MICU is wake-up mode: pulse
If none of above conditions are met: less than 0.2 V
29 --- Not used ---
30 --- Not used ---
31 HORN RLY CL- Drives horn relay With horn ON: less than 0.2 V
With horn OFF: about battery voltage
32 --- Not used ---
33 --- Not used ---
34 IG1 WIPER IG1 power source With vehicle in ON or START mode: about battery voltage
35* 1 IG2 DRL IG2 power source With vehicle in ON mode: about battery voltage
36 --- Not used ---

*1: With LED daytime running light

*2: With front fog light

UNDER-DASH FUSE/RELAY BOX CONNECTOR F (18P) (female terminals) 

GHH451832Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 +B IG MAIN2 +B power supply About battery voltage at all times
2 +B IG MAIN +B power supply About battery voltage at all times
3 +B F/BOX MAIN +B power source About battery voltage at all times
4 +B F/BOX MAIN2 +B power source About battery voltage at all times
5 --- Not used ---
6 +B H/L HI MAIN +B power supply About battery voltage at all times
7 GND Under-dash fuse/relay box ground Less than 0.2 V at all times
8 IGP Detects PGM-FI main relay 1 signal With vehicle in ON mode: about battery voltage
9 --- Not used ---
10 IG1 OPTION IG1 power source With vehicle in ON or START mode: about battery voltage
11 IG1 ACG IG1 power source With vehicle in ON or START mode: about battery voltage
12 R H/L HI Output right headlight (HI) signal With headlight (HI) is ON: about battery voltage
With headlight (HI) is OFF: less than 0.2 V
13 --- Not used ---
14 --- Not used ---
Terminal number Terminal name Description Signal
15 RR DEF RLY CL- Drives rear window defogger relay With vehicle in ON mode and rear window defogger OFF: about battery voltage
With vehicle in ON mode and rear window defogger ON: less than 0.2 V
16 HOOD SW Detects hood latch switch signal With hood latch switch ON : less than 0.2 V
With hood latch switch OFF and MICU is wake-up mode: about battery voltage
With hood latch switch OFF and MICU is sleep mode: pulse
17 S-NET Communication line ---
18 IMOFLR Drives PGM-FI main relay 2 About 0 V for 2 seconds after vehicle in ON mode, then battery voltage
With vehicle in START model: about 0 V

UNDER-DASH FUSE/RELAY BOX CONNECTOR G (4P) (female terminals) 

GHH451833Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 IG1 SWS IG1 power source With vehicle in ON or START mode: about battery voltage
2 --- Not used ---
3 --- Not used ---
4 IG1 SRS IG1 power source With vehicle in ON or START mode: about battery voltage

UNDER-DASH FUSE/RELAY BOX CONNECTOR H (13P) (female terminals) 

GHH451834Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 --- Not used ---
2 BED GATE SW+ Detects tailgate switch signal With tailgate switch ON: less than 0.2 V
With tailgate switch OFF and MICU is wake-up mode: about battery voltage
With tailgate switch OFF and MICU is sleep mode: pulse
3 --- Not used ---
4 +B INTERIOR LT +B power supply About battery voltage at all times
5 --- Not used ---
6 --- Not used ---
7 ACC RLY CL ACC power source With vehicle in ACCESSORY or ON mode: about battery voltage
8 IG1 RLY CL IG1 power source With vehicle in ON or START mode: about battery voltage
9 --- Not used ---
10 HORN SW Detects horn switch signal With horn switch ON: less than 0.2 V
With horn switch OFF: about battery voltage
With security alarm actuation: less than 0.2 V
11 INTR LT- Outputs interior light signal With interior light switch in DOOR position and interior lights ON: less than 0.2 V
12 IG2 RLY CL IG2 power source With vehicle in ON mode: about battery voltage
13 SMALL LT Detects small light signal With small lights are OFF: less than 0.2 V
With small lights are ON: about battery voltage

UNDER-DASH FUSE/RELAY BOX CONNECTOR M (12P) (female terminals) 

GHH451835Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 B-CAN_L Communication line ---
2 IG1A FBK IG1 power source With vehicle in ON or START mode: about battery voltage
3 IG1B FBK IG1 power source With vehicle in ON or START mode: about battery voltage
4 --- Not used ---
5 R TURN SIG Output right turn signal light signal With right turn signal light ON: about battery voltage
6 SMART RLY GND Ground for IG1A/IG1B relays and IG2/ACC relays circuits Less than 0.2 V at all times
7 B-CAN_H Communication line ---
8 S-NET Communication line ---
9 +B BACKUP +B power supply About battery voltage at all times
10 IG2-MAIN IG2 power source With vehicle in ON mode: about battery voltage
11 L TURN SIG Output left turn signal light signal With left turn signal light ON: about battery voltage
12 IG1 METER IG1 power source With vehicle in ON or START mode: about battery voltage

UNDER-DASH FUSE/RELAY BOX CONNECTOR N (20P) (female terminals) 

GHH451836Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 COMBI SW GND(LT) Ground for combination light switch Less than 0.2 V at all times
2 FR WIPER HI SW Detects windshield wiper switch Hi or Lo signal With windshield wiper switch Hi or Lo: less than 0.2 V
With windshield wiper switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time
3 FR WIPER INT SW Detects windshield wiper switch INT signal With windshield wiper switch INT or Lo: less than 0.2 V
With windshield wiper switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time
4 --- Not used ---
5 --- Not used ---
6 --- Not used ---
7 --- Not used ---
8 --- Not used ---
9 FR WIPER INT VOL Detects intermittent dwell timer controller signal With vehicle in ON mode: about 0-5 V (depending on intermittent dwell timer controller)
10 FR FOG SW Detects front fog light switch signal With front fog light switch ON: less than 0.2 V
With front fog light switch OFF and MICU is wake-up mode: about battery voltage
With front fog light switch OFF and MICU is sleep mode: pulse
11 COMBI SW GND(WIP) Ground for wiper/washer switch Less than 0.2 V at all times
12 FR WASHER SW Detects windshield washer switch signal With windshield washer switch ON: less than 0.2 V
With windshield washer switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time
Terminal number Terminal name Description Signal
13 FR WIPER MIST SW Detects windshield wiper switch MIST signal With windshield wiper switch MIST: less than 0.2 V
With windshield wiper switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time
14 R TURN SW Detects right turn signal switch signal With right turn signal switch ON: less than 0.2 V
With right turn signal switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time
15 L TURN SW Detects left turn signal switch signal With left turn signal switch ON: less than 0.2 V
With left turn signal switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time
16 H/L HI SW Detects combination light switch Hi signal With combination light switch Hi: less than 0.2 V
With combination light switch OFF and MICU is wake-up mode: about battery voltage
With combination light switch OFF and MICU is sleep mode: pulse
17 PASSING SW Detects combination light switch PASSING signal With combination light switch PASSING: less than 0.2 V
With combination light switch OFF and MICU is wake-up mode: about battery voltage
With combination light switch OFF and MICU is sleep mode: pulse
18 H/L OFF SW Detects combination light switch OFF signal With combination light switch OFF: less than 0.2 V
With combination light switch ON and MICU is wake-up mode: about battery voltage
With combination light switch ON and MICU is sleep mode: pulse
19 H/L ON SW Detects combination light switch ON signal With combination light switch ON: less than 0.2 V
With combination light switch OFF and MICU is wake-up mode: about battery voltage
With combination light switch OFF and MICU is sleep mode: pulse
20 SMALL LT SW Detects combination light switch SMALL signal With combination light switch SMALL: less than 0.2 V
With combination light switch OFF and MICU is wake-up mode: about battery voltage
With combination light switch OFF and MICU is sleep mode: pulse

UNDER-DASH FUSE/RELAY BOX CONNECTOR P (24P) (female terminals) 

GHH451837Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 GND MICU ground Less than 0.2 V at all times
2 --- Not used ---
3 IG1 REM IG1 power source With engine remote start operation: about battery voltage
4 HAZARD SW Detects hazard warning switch signal With hazard warning switch ON: less than 0.2 V
With hazard warning switch OFF: about battery voltage
5 TRUNK ACT RLY Detects in-bed trunk lid main switch signal With in-bed trunk lid main switch ON: less than 0.2 V
With in-bed trunk lid main switch OFF: about battery voltage
6 --- Not used ---
7 --- Not used ---
8 --- Not used ---
9 --- Not used ---
10 --- Not used ---
11 --- Not used ---
12* R LED TELLTALE Detects right LED control unit signal ---
13 --- Not used ---
14 --- Not used ---
15 --- Not used ---
16 FUEL LID CL- Drives fuel fill door opener solenoid relay With fuel fill door opener switch ON: less than 0.2 V
With fuel fill door opener switch OFF: about battery voltage
17 INTR LT CUT CL- Drives interior lights cut relay With interior lights are ON: less than 0.2 V
With interior lights are OFF: about battery voltage
18 --- Not used ---
19 TRUNK SW Detects in-bed trunk lid latch switch signal With in-bed trunk lid latch switch ON: less than 0.2 V
With in-bed trunk lid latch switch OFF: about battery voltage

*: With LED headlight

Terminal number Terminal name Description Signal
20 CARGO LT- Detects cargo area light switch signal With cargo area light switch ON: less than 0.2 V
With cargo area light switch OFF: about battery voltage
21 TRUNK KEY-CYL SW Detects in-bed trunk lid key cylinder switch signal With in-bed trunk lid key cylinder switch ON: less than 0.2 V
With in-bed trunk lid key cylinder switch OFF and MICU is wake-up mode : about battery voltage
With MICU is sleep mode: pulse
22 KEY SW Detects KEY SW signal With vehicle in OFF (LOCK) mode and MICU in wake-up mode: about battery voltage
With vehicle in OFF (LOCK) mode and MICU in sleep mode: pulse
23 SCTY(1) Detects security signal With security related unit installed: less than 0.2 V
With security related unit not installed and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: pulse
24* L LED TELLTALE Detects left LED control unit signal ---

*: With LED headlight

UNDER-DASH FUSE/RELAY BOX CONNECTOR Q (10P) (female terminals) 

GHH451838Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 --- Not used ---
2 --- Not used ---
3* FR DEF RLY CL- Drives heated windshield wiper area relay With heated windshield wiper area ON: less than 0.2 V
With heated windshield wiper area OFF: about battery voltage
4 --- Not used ---
5* FR DEF SW Detects heated windshield wiper area switch signal With heated windshield wiper area switch ON: less than 0.2 V
With heated windshield wiper area switch OFF and MICU is wake-up mode: about battery voltage
With MICU is sleep mode: less than 0.2 V at all time

*: With heated windshield wiper area

Terminal number Terminal name Description Signal
6 --- Not used ---
7 --- Not used ---
8 --- Not used ---
9 EXT BUZ Outputs keyless buzzer signal ---
10 --- Not used ---

*: With heated windshield wiper area

UNDER-DASH FUSE/RELAY BOX CONNECTOR R (16P) (female terminals) 

GHH451839Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 --- Not used ---
2 +B FR AC SOCKET +B power supply About battery voltage at all times
3 --- Not used ---
4 --- Not used ---
5* +B H/SEAT +B power supply About battery voltage at all times
6 --- Not used ---
7 --- Not used ---
8 --- Not used ---
9 K-LINE Communication line ---
10 B-CAN_H Communication line ---
11 B-CAN_L Communication line ---
12 ACC ACC power source With vehicle in ACCESSORY or ON mode: about battery voltage
13 IG1 VSA IG1 power source With vehicle in ON or START mode: about battery voltage
14 --- Not used ---
15 ILLUMI+ Detects small light relay circuit signal With interior lights are OFF: less than 0.2 V
With interior lights are ON: about battery voltage
16 --- Not used ---

*: With ventilated seat

UNDER-DASH FUSE/RELAY BOX CONNECTOR S (18P) (female terminals) 

GHH451840Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 --- Not used ---
2 R SIDE DOOR LOCK Drives right door lock actuator When right door lock actuator in locking operation: about battery voltage
3 +B AS P/W +B power supply About battery voltage at all times
4 --- Not used ---
5 R SIDE DOOR UNLOCK Drives right door lock actuator When right door lock actuator in unlocking operation: about battery voltage
6 --- Not used ---
7 --- Not used ---
8 --- Not used ---
9 +B SMART +B power supply About battery voltage at all times
10 --- Not used ---
11 --- Not used ---
12 --- Not used ---
13 --- Not used ---
14 --- Not used ---
15 --- Not used ---
16 --- Not used ---
17* DR CRTSY LT Detects driver's door courtesy light signal With driver's door courtesy light ON: less than 0.2 V
18* AS CRTSY LT Detects front passenger's door courtesy light signal With front passenger's door courtesy light ON: less than 0.2 V

*: With courtesy light

UNDER-DASH FUSE/RELAY BOX CONNECTOR T (10P) (female terminals) 

GHH451841Courtesy of HONDA, U.S.A., INC.
Terminal number Terminal name Description Signal
1 --- Not used ---
2 IG2 A/C IG2 power source With vehicle in ON mode: about battery voltage
3 BACK LT Detects reverse relay circuit signal With vehicle in ON mode and R position/mode: about battery voltage
If none of above conditions are met: less than 0.2 V
4 --- Not used ---
5 DR DOOR UNLOCK Drives driver's door lock actuator When driver's door lock actuator in unlocking operation: about battery voltage
6 DR DOOR LOCK Drives driver's door lock actuator When driver's door lock actuator in locking operation: about battery voltage
7 IG1 OPTION IG1 power source With vehicle in ON or START mode: about battery voltage
8 --- Not used ---
9 +B SUNROOF +B power supply About battery voltage at all times
10 +B DR P/W +B power supply About battery voltage at all times