C4 Keyless Entry and Alarm Repair, Part 2 - Technically Speaking

James Berry Oct 1, 2011 0 Comment(s)
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&bull If the key-in-ignition switch isn't working correctly, the PKE system will not operate. This feature is intended to prevent the system from auto-locking if you accidentally leave the key in the ignition. If the system is functioning correctly, the programmed door or doors will remain unlocked when the key is left in the ignition. Verify that you haven't accidentally left the secondary transmitter in the vehicle.
&bull To verify your that key-in-ignition switch is working, open the driver's door with the key inserted in the ignition and listen for the warning chime.
&bull If no chime is heard, you either have a defective key-in-ignition switch in the steering column or there is a wiring problem between the ignition switch and the CCM module or PKE receiver. It's also possible that the CCM module or PKE receiver is defective.
&bull To test for an intermittent open circuit within the steering column, actuate the tilt-steering-wheel mechanism while the key is in the ignition and listen for the chime. If you hear the chime while actuating the steering column, you have an open circuit in the column.
&bull You can also test for an intermittent open circuit at the key-in-ignition switch by wiggling the ignition key and listening for the chime. If you hear the chime while wiggling the key, you have a faulty switch.

A fault code 16 likely indicates that you have a malfunctioning or misadjusted door switch (common).

A fault code 17 likely indicates that you have a faulty transmitter (common). If you have two transmitters, bring your secondary transmitter into range, shake it, and see if the fault goes away. If so, your primary transmitter is faulty.

Repairing Cold Solder Joints in the PKE Receiver
Intermittent problems with electronic modules or circuit boards are often the result of a cold solder joint. Cold solder joints are quite common in remote-keyless-entry fobs and PKE receivers, as well as a multitude of other modules on Corvettes.

The term "cold solder joint" refers to a solder connection that wasn't heated enough during manufacturing, was cooled too quickly, or had its component pins moved before the solder had a chance to solidify. With time, cold solder joints can become problematic due to vibration, repeated thermal cycling, or constant exposure to high temperatures.

When diagnosing a bad solder joint, try tapping on the suspect component. If this causes it to work temporarily, you'll have a pretty good indication that you've found the problem. For example, when trying to determine why the PKE receiver would not automatically lock or unlock our C4's doors when the transmitter was in range, we found that tapping the top of the receiver briefly rectified the glitch. This led us to deduce that the PKE receiver was the culprit.

You can repair cold solder joints without knowing anything about circuitry. Use a light and a magnifying glass to examine components for hairline cracks in the solder around the pins. Fixing them will require a low-wattage, pencil-style soldering iron and some rosin-core solder, which can be found at any Radio Shack or auto-parts store.

Apply a small amount of solder to the heated iron, and then use the tip of the iron to heat the joint and apply the solder at the same time. The solder should flow evenly on the joint, repairing the connection. This process should only take a second or two. Any more, and the heat from the iron could damage the circuit board or the component itself. Repeat as needed, soldering any and all questionable connections.

Don't be afraid to try this simple repair on your Corvette's PKE. Remember, the components in question are already broken and would otherwise be discarded.

As we mentioned earlier, the C4 PKE receiver has been discontinued by GM. So if you can't repair yours, you have the option of either buying a salvage-yard replacement or sending it out to be rebuilt. If you choose the rebuild route, be sure to give the rebuilder a detailed list of your symptoms. This will help him verify that the repair has been completed before returning the unit to you. Vette

When diagnosing a bad solder joint, try tapping on the suspect component. If this causes it to work temporarily, you'll have a pretty good indication that you've found the problem.

Got a question for our Tech Corner expert? Just jot it down on a paper towel or a lightly soiled shop rag and send it to us at VETTE Magazine, Attn: Technically Speaking, 9036 Brittany Way, Tampa, FL 33619. Alternatively, you can submit your question via the Web, by emailing it to us at vette@sorc.com. Be sure to put "Technically Speaking" in the subject line.


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