This tutorial will help you test the ignition switch on the 1997 Chevrolet and GMC Pick Up, Suburban, Tahoe, and Yukon equipped with a 4.3L, 5.0L, or a 5.8L V8 engine.
The ignition switch test involves checking for continuity across specific terminals of the ignition switches connector.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Probar El Interruptor De Encendido (1997 Chevrolet/GMC Pick Up Y Suburban) (at: autotecnico-online.com).
Symptoms Of A Bad Ignition Switch
The most common symptom of a defective ignition switch is an ‘engine does not crank’ problem.
To be a bit more specific, your turn the key to crank and start the engine but nothing happens. Everything works (headlights, wipers, horn, radio, power windows, etc.) but the starter motor won't crank the engine.
The other common symptoms is that the accessories don't work with the Key On or in Run. By accessories I mean like the radio, dash lights, etc.
You may also see one ore more of the following:
- Your Chevy pick-up cranks, but won't stay running unless you hold the key slightly forward.
- Smoke came out from under the steering column's plastic covers (before the problem started).
- The engine cranks, but doesn't start.
Now, if you think the starter motor may be the cause of the problem, the following tutorial will help you test it:
Ignition Switch Test Basics
The ignition switch, on the 1997 Chevrolet and GMC pick up and SUVs covered by this tutorial, have 5 positions. These are: ACC, LOCK, OFF, RUN, START.
When you turn the key to any one of these positions, the ignition switch simply ‘opens’ or ‘closes’ certain circuits (wires) together.
This action of ‘opening’ or ‘closing’ those circuits will either let current pass (or cut it off) from one wire (circuit) to another.
Using the illustrations in the image viewer, here's a brief description of the circuits that make up the ignition switch.
Although the ignition switch has 42 slots on its electrical connector, we only need to continuity test a few specific terminals to find out if it's defective or not.
With these basics, let's jump into the next subheading and get testing.
Continuity Tests Of The Ignition Switch
Testing the ignition switch involves checking the continuity between certain terminals of the ignition switch's connector.
When performing the continuity checks, you're simply looking for a continuity or no-continuity test result. Yup, there isn't a specific resistance value that you're looking for (or that I can give your for each test).
A continuity test result means that your digital multimeter will read an Ohms value. A no-continuity test result means that your multimeter will read OL.
From personal experience I can tell you that to get the best test result, you should use a digital multimeter. If you don't have one, you can check out my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing.
NOTE: All continuity tests are done on the connector of the ignition switch itself. This connector has female terminals. You can identify the specific terminals that we need to test with the help of image 2 of 2 in the image viewer above.
These are the test steps:
Disconnect the negative terminal from the negative battery post.
Disconnect the ignition switch from the vehicle wiring harness connector at the base of the steering column.
Place your multimeter in Ohms mode.
Place the ignition key in the ACC position.
You should have continuity between terminals D2 and D6 of the ignition switch connector.
Place the ignition key in the OFF position.
You should have continuity between terminals C1 and D5 of the ignition switch connector.
Place the ignition key in the RUN position.
TEST A: You should have continuity between terminals C1, C5, and D5.
TEST B: You should also have continuity between terminals C6, D2, and D6 of the ignition switch connector.
Hold the ignition key in the START position.
You should have continuity between terminals C1, C5, D1, and D5 of the ignition switch connector.
Let's interpret your test results:
CASE 1: Continuity exists between the indicated terminals. This test result tells you that the ignition switch is OK and not defective.
CASE 2: Continuity DOES NOT exist between some or all of the indicated terminals. This test result tells you that the ignition switch is defective and needs to be replaced.