How To Test The Knock Sensors (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon)

TEST 2: Testing Knock Sensor 2 (Rear Sensor)

Testing knock sensor 2 follows the same procedure as testing knock sensor 1.

The difference between tests is that you'll be testing the light blue (LT BLU) wire instead of the DK BLU one.

In the photo above, I've labeled the LT BLU wire with the letter B.

RESISTANCE SPECIFICATION: The resistance specification of knock sensor 2 is 93 to 107 K Ohms.

Let's get started:

1. 1

   Place your multimeter in Ohms mode.

2. 2

   Disconnect the knock sensors jumper wiring harness.
   
   The knock sensors jumper wiring harness is located on the left side (driver side) of the intake manifold. See photo above.

3. 3

   Connect the red multimeter test lead to the male terminal that connects to the light blue (LT BLU) wire of the connector.
   
   The LT BLU wire is identified with the letter B in the photo above.
   
   NOTE: This test is done on the knock sensors jumper wiring harness connector that has male spade terminals.

4. 4

   Ground the black multimeter test lead directly on the battery negative (-) post.

5. 5

   You should see a resistance value between 93 to 107 K Ohms on your multimeter.

Let's analyze your test results:

CASE 1: The resistance of knock sensor 2 is within the indicated range. This is the correct test result and it lets you know that knock sensor 2 is good.

You can also conclude that there are no wiring problems with the knock sensors jumper wiring harness.

If the engine is knocking (pinging), then this test result lets you know that the source of the problem is an engine mechanical problem.

CASE 2: The resistance of knock sensor 2 IS NOT within the indicated range. This test result generally lets you know that knock sensor 2 is bad and needs to be replaced.

The next step is to remove the intake manifold and:

• Visually inspect knock sensor 2 and see if it's damaged or corroded.
• Visually inspect the knock sensors jumper wiring harness for damage or corrosion.

Replace any component that is damaged/corroded.

More Silverado, Sierra, Suburban, Tahoe, And Yukon Tutorials

You can find a complete list of V8 Chevrolet Silverado (GMC Sierra) tutorials in this index:

• GM 4.8L, 5.3L, 6.0L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• Resistance Specifications Of The TAC Electronic Throttle Body.
• How To Test The GM Accelerator Pedal Position (APP) Sensor 2.
• How To Test The MAF Sensor (GM 4.8L, 5.3L, 6.0L, 8.1L).
• Blown Head Gasket Test (GM 4.8L, 5.3L, 6.0L).