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Which wires give constant, ignition and ground on a 2018 Toyota Corolla?
On a 2018 Toyota Corolla, take constant power from the Blue wire at the ignition switch (key cars), white 8-pin plug, pin 4, ignition from the Gray wire at the ignition switch, white 8-pin plug, pin 3, and ground to clean, bare body metal. Meter every wire first.
Written by API Signal, fleet GPS and camera installers for 35+ years across Georgia, South Carolina and North Carolina, installing every major telematics and camera brand. Every wire on this page lists its source.
Test every wire with a meter before you tap it
No wiring information is ever guaranteed. Colors and locations change with trim, options and build date, and the manufacturer can change them in the middle of a model year. We share this as a starting point for installers, and you are responsible for confirming every connection on the truck in front of you.
This page covers the 2018 Toyota Corolla sedan.
The Corolla came with a key or push-button start. Maker guides confirm the power wires and the CAN tap for 2017 to 2019. No body wire list was found for these years, so turn, brake, reverse and door wires show Not found. Our own team has not yet metered these on a 2018 car.
OBD-II portLocation not confirmed
Best power spotIgnition switch plug or steering lock plug
System voltage12V
Ignition typeKey or push-button
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Where do I get constant, ignition and ground on a 2018 Toyota Corolla?
Take constant, ignition and ground from the same area.
Option 1 Key cars
Ignition switch plug
Key cars. Steering column, white 8-pin plug.
Constant
Blue
Ignition switch (key cars), white 8-pin plug, pin 4Always hot.
Ignition
Gray
Ignition switch, white 8-pin plug, pin 3Hot in run. A second ignition wire, Green, is on pin 8.
Ground
Body ground
Body metal under the dashClean, bare metal only. Never the battery negative post.
Accessory
Black
Ignition switch, white 8-pin plug, pin 7Hot in accessory and run.
The starter is White on pin 2. Never tap the starter. The main battery feed is a White 120A wire on the dash fuse box white 1-pin plug; do not tap it for a small device.
Option 2 Push-button
Steering lock plug
Push-button cars. Under the steering column, black 7-pin plug.
Constant
Blue
Steering lock plug, black 7-pin, pin 7Always hot.
Ignition
Gray or Green
Steering lock plug, black 7-pin, pin 6Hot in run. iDatalink says this wire can be Gray or Green on 2017 to 2019 cars.
Ground
Body ground
Body metal under the dashClean, bare metal only. Never the battery negative post.
From the iDatalink guide for push-button cars. The steering lock is under the steering column.
Key-car colors from the iDatalink install guides for 2017 to 2019 and Directed (2017). They match the 2014 to 2016 plug. Push-button colors from iDatalink.
What are the turn signal, reverse and light wires on a 2018 Toyota Corolla?
Circuit
Wire color
Location and what it does
Left turnNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
Right turnNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
Park lightNegative -Not yet checked
White
Main body ECU at the bottom of the dash fuse box, white 30-pin plug, pin 30Negative trigger for the park lights, from the iDatalink guide for push-button cars. No positive park light wire was found for these years.
HeadlightNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
ReverseNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
Dome lightNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
Each chip shows the main insulation color with its stripe. Source: the iDatalink guide for 2017 to 2019.
Where are the brake, door, speed and CAN wires on a 2018 Toyota Corolla?
Circuit
Wire color
Location and what it does
BrakeNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
DoorsNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
TrunkNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
Parking brakeNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
HazardNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
SeatbeltNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
Vehicle speedNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
TachNot foundNot yet checked
Not found
Not foundNo 2017 to 2019 wire list was found. The 2014 list is on the 2016 page, but nothing confirms it after the 2017 facelift.
CAN busDataNot yet checked
Black (high)
White (low)
Body ECU plug under the dash fuse box, white 30-pin, pins 14 and 13For 2017 to 2019 the makers take CAN here, not at the OBD port. Directed still lists Red and White at OBD pins 6 and 14 for 2017. Never cut or splice them.
Sources: the iDatalink guides for 2017 to 2019 and Directed's guide for 2017. No installer wire list was found for these years, so most body circuits show Not found.
Which years share wiring with the 2018 Toyota Corolla?
This page2018Covered by the maker guides for 2017 to 2019.
Same wiring2017 and 2019iDatalink lists 2017 to 2019 as one install. The ignition switch plug matches 2014 to 2016, but the CAN tap moved.
Not this page2016 and older or 2020 and newerBefore the facelift, with a full wire list, or the next body with different colors and pins.
Where are the fuse boxes and ground points on a 2018 Toyota Corolla?
InteriorUnder the dash, left side, under a lidGo by the fuse name on the lid: P/OUTLET (15A), ACC (7.5A), OBD (7.5A). Two fuse guides number these slots differently.
Under the hoodLeft side of the engine bayRADIO (20A) and DOME are here.
Ground pointsClean body metalNo named ground point was found. Never use the battery negative post.
Fuse names from fuse guides for 2014 to 2018 cars. They disagree on slot numbers and on some amp ratings, so read the lid label and meter the slot.
Where is the OBD-II port on a 2018 Toyota Corolla?
OBD II
Diagnostic portOBD-II port: location not confirmedLook under the driver side dash first, and send us a photo if you find it.
Common questions about 2018 Toyota Corolla wiring
What wire is constant power on a 2018 Toyota Corolla?
Blue at the ignition switch (key cars), white 8-pin plug, pin 4. Always hot. Meter it before you tap it.
What wire is ignition on a 2018 Toyota Corolla?
Gray at the ignition switch, white 8-pin plug, pin 3. Hot in run. Meter it before you tap it.
Where is the CAN bus on a 2018 Toyota Corolla?
Black (high) and White (low) at the body ECU plug under the dash fuse box, white 30-pin, pins 14 and 13. For 2017 to 2019 the makers take CAN here, not at the OBD port.
Which years share wiring with the 2018 Toyota Corolla?
2017 and 2019. iDatalink lists 2017 to 2019 as one install.
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