Chevy Ignition Switch Wiring Diagram: Terminals and Key Positions

A Chevy ignition switch is a rotary switch that connects battery power to the accessory, run and start circuits depending on where the key sits, and on the GM vehicles in NHTSA’s ignition recalls that key position also affects the airbags. GM’s 2019 Silverado manual lists four positions: LOCK/OFF, ACC/ACCESSORY, ON/RUN and START. This chevy ignition switch wiring diagram guide explains what the BAT, ACC, IGN and start terminals do, why wire colors differ, and what the 2014 GM ignition recalls show about the run position. It does not list factory wire colors by year; those belong to your service manual.

What Those Four Terminals Actually Do

The switches in the sources below do four jobs: pass battery power in, then hand it to the accessory circuit, the ignition (run) circuit and the starter solenoid. Makers label the posts differently. The labels below come from two American Autowire (AAW) instruction sheets: kit sheet 500404 (ignition switch and starter wiring kit, revision 4.0, 1/14/2004) and sheet 510737 for its 1947-55 Chevy and GMC truck switch (revision 0.0, 10/8/2019).

Terminal label	Circuit it serves	AAW wire color	What the sheet says
BAT	Battery feed into the switch	Red	The red main battery wire runs to the switch BAT terminal; the other end goes to the BAT stud on the starter solenoid through a fuse link
ACC	Accessory feed	Brown	The brown wire runs to the ACC terminal and feeds the accessory circuit
IGN	Ignition (run) feed	Pink	The pink wire goes to the IGN location on the switch and to the coil, an HEI distributor input, or a ballast resistor feed-in side
START (marked SOL on both sheets)	Starter solenoid feed	Purple	The purple wire connects to the solenoid SOL terminal; a neutral safety switch, if used, is installed in line with this wire
GRD (1947-55 switch only)	Ground post	None	The 510737 sheet labels the ground wire “do not use” on its connector diagram

The colors are AAW’s kit colors for its replacement wiring, not the colors GM used at the factory, and the labels are the switch maker’s, so a late-model switch with a multi-pin plug will not match them one to one.

AAW’s sheet 500404 also shows where GM column switches differ: for a GM steering column switch, each wire instruction says to use a separate parts bag (500257) and follow that bag’s instructions. For the starter side of the same circuit, see our starter ignition switch wiring diagram and the Chevy starter solenoid wiring guide.

Myth: The Wiring Colors Are Standard Across All Chevys

They are not, and the sources show why. AAW’s own two sheets, written 15 years apart for different products, use the same convention: red for battery, brown for accessory, pink for ignition, purple for the starter solenoid. That consistency belongs to one aftermarket maker, not to the harness already in your dash.

GM tells owners where the real information lives. The 2019 Silverado manual says the dealer and the service manual have information about servicing the vehicle and the airbag system, and it points to its publication ordering section for buying a service manual. That is the document to use for a year-specific diagram, pin numbers and connector views. Copied color charts for an ’84 GMC or a ’75 Chevy are not a substitute.

For older trucks, our 70s Chevy starter switch wiring guide covers that era, and the steering column ignition switch wiring page covers the column side.

Key Positions and Which Circuits Are Live

This is the part most diagrams skip. GM’s 2019 Silverado manual describes what each key position does for the driver, and those functions map onto the circuit names above. The manual does not list terminal-level voltages, so treat the right-hand column as the circuit family, not a measured reading.

Key position	What GM’s manual says it does	Circuit family
LOCK/OFF	Turns off the vehicle and locks the ignition, the automatic transmission and, if equipped, the steering column	Run and start circuits off; Retained Accessory Power can stay active
ACC/ACCESSORY	Lets features such as the infotainment system work with the vehicle off and unlocks the steering column; use it if the vehicle must be pushed or towed	Accessory feed
ON/RUN	Operates electrical accessories, shows warning lights and stays here while the engine runs; also unlocks the transmission on automatics	Accessory plus ignition (run) feed
START	Starts the engine; release the key and it returns to ON/RUN	Starter solenoid feed (momentary)

Two practical points come from that manual. If the key is left in ACC or ON/RUN with the engine off, the battery could drain and the vehicle may not start. And Retained Accessory Power keeps the audio system and power windows working for up to 10 minutes after the ignition is turned off, so a feature working with the key out is normal, not a wiring fault.

The manual also gives the reason the run position matters beyond convenience: turning off the vehicle while moving may cause loss of power assist in the brake and steering systems and disable the airbags, so it should only be done in an emergency.

Why the Run Position Matters for Airbags: GM’s Ignition Recalls

The same sentence appears across several GM recall records on NHTSA’s site: if the key is not in the run position, the airbags may not deploy in a crash. That turns a wiring diagram from a hobby reference into a safety topic. The records below are the Chevrolet-relevant ones, summarized from NHTSA’s campaign data and the GM recall bulletin for the Camaro.

NHTSA campaign	Chevrolet models listed	What can move the switch	Remedy NHTSA records
14V-047	2005-2007 Cobalt; 2006-2007 HHR; certain 2008-2010 Cobalt and 2008-2011 HHR (also Pontiac and Saturn models)	Key ring weight or road conditions can move the switch out of the run position	Dealers replace the ignition switch, free of charge
14V-355	2006-2014 Impala; 2006-2007 Monte Carlo (also Buick and Cadillac models)	Key ring weight and road conditions or another jarring event	Two key rings and a slot insert or head cover on the ignition keys
14V-346	2010-2014 Camaro built December 3, 2008 to May 23, 2014	A driver’s knee can knock the key out of run	Key blade removed from the flip key; two new keys and key rings supplied

NHTSA lists 2,190,934 vehicles as potentially affected in 14V-047, 3,141,731 in 14V-355 and 464,712 in 14V-346. The 14V-047 record adds that the defective switches may have been used as service replacement parts on other vehicles, which is why the recall grew to later model years, so a switch installed years ago still deserves a recall check. NHTSA’s 14V-047 interim guidance was to remove all items from the key ring, leaving only the ignition key and taking any key fob off the ring. The NHTSA recall page for 14V-047 carries the full record.

For the 2010-2014 Camaro, the GM bulletin states the condition plainly: some drivers may bump the ignition key with a knee, engine power and power braking are affected, power steering may be affected, and the airbags may not deploy depending on timing. Until the recall is performed, it says to adjust the seat and steering column so there is clearance between the knee and the key. A recall-affected vehicle needs the recall repair, not a rewire.

Immobilizers and Anti-Theft: Why a Swap Is Not Just Four Wires

On a late-model GM truck the key does more than turn a switch. The 2019 Silverado manual describes a passive theft-deterrent system: the vehicle is immobilized automatically when it is turned off and disarmed when the ignition is turned from off to on. Up to eight keys can be programmed to the vehicle, and the manual says to see the dealer for a new key blank cut to match the ignition key.

That is why a switch swap on a newer Chevy is not the four-wire job the kit sheets describe: those sheets cover a 1947-55 truck switch and a general kit, with no key-coded immobilizer to match. If your vehicle has a security light, key and system have to agree, which is dealer or locksmith work.

Classic Chevy and GMC Truck Switches: What the 1947-55 Sheet Shows

For old trucks the AAW 510737 sheet is the useful reference. It describes a switch with posts marked SOL, ACC, GRD, BAT and IGN, a dash harness connector viewed from the back, and two installation paths: one for 1947-53 applications and one for 1954-55 applications, with the 1954-55 path needing a pinch-welded dashboard flange filed flush. In both, the existing lock cylinder is inserted into the new switch and the switch is positioned so the off/lock position is straight up and down before the collar is tightened.

Sheet 500404 adds a starting-circuit detail for points ignitions: a yellow wire from the solenoid R terminal to the ballast resistor feed-out side. That terminal sits on the starter, which corrects the common idea of an R post on the key switch.

Working Safely Around the Switch and the Airbags

The ignition switch sits behind the steering wheel, and GM says airbag parts are in several places around the vehicle. These cautions come from GM’s owner manual and apply before any dash or column work:

• For up to 10 seconds after the vehicle is turned off and the battery is disconnected, an airbag can still inflate during improper service. GM warns that you can be injured if you are close to an airbag when it inflates.
• Avoid yellow connectors. GM says they are probably part of the airbag system.
• Changing or improperly repairing airbag modules, sensors, the sensing and diagnostic module or airbag wiring can stop the airbag system working properly.
• How to disconnect the battery and when to wait is spelled out in the factory service manual for your vehicle; follow that procedure rather than a generic one.

Stop and use a dealer or qualified shop if the key sticks, if the key can be removed in a position other than LOCK/OFF (GM says to see your dealer for that), if the airbag readiness light stays on, or if the engine shuts off while driving. A meter such as the one in the box is for confirming a circuit the service manual identifies, never for probing airbag wiring.

Keep reading

• How To Turn On A Car With A Bad Ignition Switch (Safe Steps)
• Chevy Key Fob Battery Replacement: The Complete DIY Guide
• Chevy Silverado Under Hood Fuse Box Diagram: Full Guide (2026-2026)

Frequently Asked Questions

Why does my Chevy crank but not start?

Check the theft-deterrent system first. GM’s 2019 Silverado manual says that if the engine does not start and the security light stays on, turn the ignition off and try again, then try another key and check the fuse. If it still will not start, the vehicle needs service.

Can I use a universal ignition switch on my Chevy?

Sometimes on a classic truck, rarely on a newer one. American Autowire offers its kit in GM column mount, dash mount and universal versions, and sends GM column owners to a separate instruction bag. A vehicle with an immobilizer ties key and ignition together, so a swap belongs with a dealer or locksmith.

What is the R terminal in a Chevy starting circuit?

On American Autowire’s kit sheet 500404 the R terminal is on the starter solenoid, not the ignition switch. A yellow wire runs from it to the feed-out side of the ballast resistor for the starting circuit of a points ignition, and the sheet gives separate coil wiring for systems that need only a 12-volt feed.

Can a heavy key ring really turn off a Chevy engine?

For specific GM vehicles, yes. NHTSA recall 14V-047 says key ring weight or road conditions may move the switch out of the run position and turn off the engine, and then the air bags may not deploy. Check your VIN for open recalls.

Is it safe to bypass the ignition switch to start my truck?

No, and this guide gives no bypass steps. GM’s manual warns that turning off a moving vehicle may cause loss of power assist in the brake and steering systems and disable the airbags. For a lost key or a failed switch, call a dealer or a locksmith.

This guide does not cover factory wire colors or pin numbers for a specific year; use the factory service manual for that. It does not cover hot-wiring or any bypass of the key, and it gives no repair prices.