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EGR TEMPERATURE SWITCH
This page was developed for those who are having problems with the ecm setting a trouble code involving the egr system. A code 32 is set whenever the ecm sees the egr switch closed on start up or the egr switch is not closed when the ecm activates the egr.
Below is a typical egr diagram:
You can check the egr temperature switch circuit by hooking up a digital meter to ecm pin C15. There should be 12V at this connection. Test drive the vehicle while observing the voltmeter. When the egr is commanded to open the voltage will drop to zero. If this does not happen, check the continuity of the wire from the ecm to the egr switch connector, with it disconnected, if the wire checks out, replace the egr temp. switch.
You can check the egr valve for proper operation by starting the engine, letting it warm up. Pull the vacuum line to the egr valve, and hook up a hand vacuum pump going to the valve and apply vacuum. If the egr is working properly, it will open up, and stall the engine, or at least cause the idle to drop. The egr is working at this point. Hook the vacuum line back up. back probe the gray wire on the egr solenoid connector and ground the wire to a good ground. If the solenoid valve works, it will do the same as the vacuum test. This test assures that the solenoid is functioning. if any component fails the test, replace it.
Now if you want to attempt to fix a faulty but still functioning egr switch here is how I did it. The egr switch is basically a bimetal strip that expands with temperature and makes contact with the metal contact pin that screws in the top of the switch. Maladjustment and age is what causes them to "fail". The fix I have attempted may not work in all cases, but may be worth a try if you are tight on funds, or don't have access to parts.
The picture above is just my representation of what is inside the switch.
Picture of (A) EGR temp. switch (B) contact pin with wire lead connector and (C) a small 6-32 NF nut that will be used to lock the contact pin in place OR you can use a drop of a high temperature thread locking compound available at most automotive stores. If you are using a nut to lock the contact pin, install it before proceeding with next step.
The picture above shows the set up for testing the switch. (A) is the egr switch. (B) Is the contact pin wire lead and connector, hook one end or f your continuity tester to this point. (C) is the continuity tester. (D) Hook the other end of tester with a jumper wire to the vise, in this case, or if you are using a pair of vise-grip pliers. Double check your tester, by touching the tester end (B) to the egr switch and make sure the tester lights up, if not find and correct problem before proceeding. If the lamp comes on with everything properly hooked up, adjust the contact pin in egr valve until light goes out.
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WARNING!! Observe safety precautions when using a propane torch! Use ONLY a propane torch for this test! When you heat up the end of the egr switch (1) the tester light (2) should come on in about 2-15 seconds or so, depending on how far the contact pin is adjusted. If the light does not come on try adjusting the contact pin until it does, but BE CAREFUL when working around the open flame of the torch while doing this, use a pair of pliers to turn contact pin!
With the pin adjusted and light on, remove the flame from the egr switch, the test light should go out in a few seconds. If it does not, turn the contact pin ccw until the light does go out. reheat the switch again, the light should come on, remove heat, the tester light should go out. You may have to repeat the steps a couple of times until the test light reacts with 3-5 seconds. When you have achieved this, turn your torch off and let the egr switch cool for a few minutes.
Use a wrench appropriate to the size of nut (6), use a pair of pliers(5) to hold contact pin while you tighten the nut. Repeat the test steps to insure the egr switch will activate promptly.
If you are using a thread locking compound, be sure to measure within a 1/32" or less of the amount of threads above the body of egr switch. Remove the contact pin and clean thoroughly with a small brass brush or equivalent, then just put one small drop of compound on threads of contact pin and screw it back into egr switch, down to the number of threads or measured height. Let it set for a few minutes. Retest to insure egr switch activates properly.
If all else fails and it still fails to respond properly, you'll need a new one.
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