QuestionQUESTION: I have a 1990 deville 4.9L that I was told had a fuel flooding problem. When it was delivered, there was no ignition key or battery. I bought an ignition tumbler/housing assembly and wired it correctly to the harness. With a fresh battery, I get no power. no dash, ignition, voltage of any kind. There was some "ground repairs" to wiring for front headlamps and running lights, and some under-dash wiring seeming out of place.
Where do I start? the new ignition keys are not like the resistor pellet OEM type, but I assumed that the after-market tumbler assembly would close the circuit on the two wires running through the column to the connector. Is this correct? Or, do I need to have a resistor key cut to the new key? I have a few diagrams, could this be related to anti-theft rather than massive short? Also, the trunk lock was popped out one night by someone unknown who evidently needed into the trunk. I know on a Tahoe I worked on I had to replace the VCM and the Power Steering Control Unit to fix a no serial data DTC problem. Could it be a component? I need a step-by-step to test the power to the vehicle. Please help
ANSWER: Anthony,
I hate to say it but you installed the wrong lock cylinder. You need to use the Pass-Key type cylinder with the proper ignition key. A locksmith "can" ID what key to use and in this case may be the easiest way to go for you. Otherwise, there's going to be a good deal of trial and error trying to figure which one of several keys is the right one. I also wanted to mention that this is only for getting the car started. As far as no power period, I'd start by checking the battery cables, then main fuses (maybe fusible links), then move up to the ignition switch under the dash. It's possible that there was some sort of aftermarket security system on the car, that was haphazardly removed, thereby leaving some major circuits disconnected.
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QUESTION: The cylinder I bought through carquest ($80.00), is identical and included two keys. I Removed the old cylinder mainly because there was also a cylinder in the glove box when I got this thing, so without knowing if either was the original, I didn't want to have a key cut from VIN. # and find out that neither one was original or functional. So I assumed that the new one would be ready to go with the keys included. At any rate, if the new cylinder came with keys, I still need a resistor key made using a new key as cut pattern? and if this is so, would the correct OEM resistance stay the same? or would the cylinder determine the resistance? Should I disconnect the plug and see if there is continuity between the 2 wires when key is indexed to start or run? Should the instrument cluster power up even with a regular key like the resistance only effects the starter? I just want to make sure if I have to make a key that the plain key is the initial problem and the resistance is correct if I have a key cut. I have done some nasty wiring before, intermittent shorts, phantom grounds, and such, Even had a GM that the dealer threw parts at, at a cost of $1400.00 and never found the problem, which was a rebuilt motor after installation, the installer grounded the main ground atop a plastic coated secondary mount at the block. This seemed to not only cause intermittent voltage sweeps and charging failure, but effected their diagnostic equipment as well. Once the ground was proper, (took about 40 minutes to find it and correct the ground issue), everything was normal. *The dealer who had serviced it (3 times) subsequently refused refund the customer for the Computer, 2 Alternators, Battery, and Diagnosis/labor charges. I am not sure I get how the resistance comes into play at this point (if the new cyl is correct) to engage the ignition, post. I appreciate the response so expeditiously.
Best Regards,
AnswerAnthony,
The way the Pass-Key system works is that the module has a programmed-in resistance that must be presented during the start sequence. If, for any reason, it does NOT see the proper resistance, the module tells the ECM/PCM there's a "Pass-Key fault". This causes the starter enable relay to NOT be energized and the message "Pass-Key fault" to be displayed at the IP. The resistance is from the little pellet on the key. The lock cylinders are all the same, they only read what the key presents.
When you buy a Pass-Key lock cylinder, it usually comes with a cheap-looking brass key blank that is only there as a cut guide for the actual pelletized key blank.
Now just remember that the system is checking for a resistance at the module so any part of the system from the module out to the key can have an effect on the system's total resistance. For this reason, you should compare the whole circuit's resistance to that of the key alone. I've seen instances where the key was good but due to a bad circuit connection or short, the module did not see the proper resistance.
Hope this helps.
