Component Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

Relay Test

Ignition OFF, disconnect the KR121B Reductant Control Module Relay 2.
Test for 70 - 110 Ω between terminals 85 and 86 of the relay.
- If not within 70 - 100 Ω
  Replace the relay.
- Go to next step: If within 70 - 100 Ω
Test for infinite resistance between the following terminals listed below:
- 30 and 86
- 30 and 87
- 30 and 85
- 85 and 87
  - If less than infinite resistance
    Replace the relay.
  - Go to next step: If infinite resistance
Install a 20 A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground.
Test for less than 2 Ω between terminals 30 and 87.
- If 2 Ω or greater
  Replace the relay.
- Go to next step: If less than 2 Ω
All OK.