I have a 1994 Jeep Grand Cherokee with a 4.0 liter engine and about 90,000 miles. Car was starting fine. I tried to start the car after a trip to a Sam's Club and the car would not start or turnover at all. The Sam's service tech tried a new battery for me and it made no difference, but I noticed the ignition switch felt "soft" and had a dead spot in it. I pulled the switch out and the lock cylinder feels very funny, but I am not sure. Is there a good way to test the ignition switch and/or the lock cylinder?

Hello again! Yes, it's the wife's Olds giving us fits again. As a refresher, it's an '89 model 88 Royale Brougham, 3.8l fuel injected v-6 and 4-speed automatic trans. Check engine light is on constantly, and reading codes gives 63, 64 and 65. My Haynes manual says they all mean EGR flow check for that engine. I had the EGR valve off to check for blockage, but found none. I cleaned off/out what carbon was present and replaced the gaskets, but still have the light. No, I haven't disconnected the battery to clear the codes; I don't want erase my wife's radio presets just yet. The EGR valve is of the three-solenoid electric variety, and there is a 4-wire connector at the top of the assembly. I figure one hot wire for each solenoid and a common ground. Please correct me if this is wrong. Now, how does the ECU know whether the EGR valve/s is/are opening? Is there a sensor in the valve assembly, or is the O2 sensor responsible for this? Also, can I test the EGR valve for proper function with common tools, or even at all? Any insight will be greatly appreciated! Thanks - Chris