How to: Delco Radio Wiring

By Jan Benschop

Updated September 28, 2017

Items you will need

  • Test light

  • Wiring harness adapters

  • Multimeter

  • Nylon, closed-end 22- to 16-gauge crimp connectors

  • Crimp tool

  • Wire cutter/stripper

American-made GM products have all been made with Delco electronics, the automaker's "house brand." Standard GM radios, whether they were installed in Chevy subcompacts, Cadillacs or GMC trucks, are all Delco radios with a standard set of plastic plugs and wire colors. Some models have all the bells and whistles and have more wires for more accessories, power connections or speakers. Models up to 1989 or 1990 have a different set of plugs and color codes from models manufactured subsequently.

Older (Up to '89 to '90) Delco Radio Wiring

Locate three plastic plugs fanned out of a single harness bundle. Plug colors are blue, white and black. Each plug has four pin positions and may have four corresponding wires. All plugs are almost square, and have alignment ridges that guide insertion to specific slots at the rear of GM radios. A fourth, smaller and flatter plug may accompany the other three. This plug is usually connected for electronic preset and clock memory.

Locate the following colors on the blue plug for rear speaker connections:

Right: Negative=light blue, Positive=dark blue Left: Negative=yellow, Positive=brown.

Locate the following colors on the white plug for front speaker connections:

Left: Positive=tan, Negative=light gray Right: Positive=light green, Negative=dark green

Locate the following colors on the black plug for power connections:

Yellow=12 volts ignition, black=ground, gray=illumination, pink, if present, activates a power antenna.

The small, flat plug has an orange wire to a 12-volt battery for preset and clock memory.

Trace each wire through the adapter plugs, strip the ends applicable to the stereo you are installing and use crimp connectors to mate the wires with the stereo's output wires. Use a test light to test power and illumination connections. Use a multimeter to test for ground wire continuity and speaker connections.

Newer ('90 and up) Delco Radio Wiring

Find a harness bundle with two four-connection plugs for speakers, and one six-connection plug for power connections.

Find the following colors on the front-speaker, four-connection plug:

Light gray=left negative, tan=left positive. Light green=right negative, dark green=right positive.

Find the following colors on the rear-speaker, four-connection plug:

Light blue=right negative, dark blue=right positive. Yellow=left negative, brown=left positive.

Find the following colors on the six-connector plug:

Yellow=12 volts switched Black=ground Gray=dimmable illumination Pink=power antenna activate Orange=12-volt battery wire for preset and clock memory

Trace each wire through the adapter plugs, strip the ends applicable to the stereo you are installing and use crimp connectors to mate the wires with the stereo's output wires. Use a test light to test power and illumination connections. Use a multimeter to test for ground wire continuity and speaker connections.

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