Permanent CR2-12 Window Relay Repair Using Replaceable Relay

dreamalaska · January 4

This write up is about replacing the CR2-12 NAIS relays found on older generation Lexus and Toyotas located on the window/door lock control switch circuit board under the switches on the driver and passenger front door. As many of you know, over time the contacts inside the CR2-12 relay start failing, causing intermittent open and close window issues which most people believe is the start of a window motor failing (it’s usually not). After researching many posts posted over the years, here’s an inexpensive repair (US$30) that will finally solve this issue. Many thanks to all who have previously taken the time to write up solutions - this fix is based on all of their previous work. This repair has changed over time due to different availability of replacement relays. The best thing about this particular repair solution is that it uses easily replaceable relays for if/when they ever go out again.

The parts listed here are currently (Dec 2023) found on Amazon:
1. 5-Pin Relays with pigtails

https://www.amazon.com/Nilight-Automotive-Harness-Interlocking-Socket/dp/B0748F1JK4/ref=sr_1_4?crid=33DUWMM0WILGO&keywords=Nilight%2B5%2Bpin%2Brelay&qid=1704045297&sprefix=nilight%2B5%2Bpin%2Brelay%2Caps%2C175&sr=8-4&th=1)

(Nilight 50003R Automotive Set 5-Pin 30/40A 12V SPDT with Interlocking Relay Socket and Wiring Harness-5 Pack, 2 Years)

2. Solder:

3. Solder Wick (to remove existing solder):

4. 30 Watt soldering iron.

After desoldering and removal of the old existing CR2-12 relay, here’s the schematic showing which pin holes to wire/solder the pigtails onto the circuit board. IMPORTANT: NOTE THE PROPER ORIENTATION OF THE PIN HOLES BEFORE SOLDERING THE NEW RELAY HARNESS WIRING. THE “TRICK” IS TO VERIFY THE LOCATION OF THE SIDE WITH 3 PINS.

Here’s what the soldered wiring looks like:

Of note, since the pigtail wiring is a much heavier gauge and designed for a greater load capacity, I had to cut off around 2/3rds of the end strands to fit through the circuit board holes.

The off-white plastic protective circuit board cover needs the lip above the existing wire harness trimmed off using a utility knife or Dremel.

After the repair there’s plenty of room to put the new relays behind the door panel:

There are minor steps that I skipped, but based on the pics you can figure it out.