Originally Posted by 07 chevy New Body

I have a 2007 chevy truck new body style. Anyway on Sunday I got off work started my truck the ses light came on so I was like great probably a bad o2 sensor or something easy. But I went to start it monday nothing the dash lights come on the radio comes on but nothing I checked the battery and got a new one still nothing so I checked my contacts they where good. Scanned the truck with some cheap code reader only scanner nothing but my ses and abs light are on and that's it. So I tried my other set of keys same thing. My key fob won't unlock or lock the doors and the switches don't unlock or lock either so im at a loss with my truck any advice because I don't want to have to tow it to the dealership and they charge me out the *** to fix something easy you .

Originally Posted by jondoe28

Had this done a couple of weeks ago. Hasn't acted up once, security hasn't come on at
all either. Hired our tractor mechanic to do it. Said 2 contacts were burnt on key switch.
Used sand paper to clean them, and good to go. Cut and pasted from another site:



I just fixed my 2002 impala security light issue. It cost me 2 hours, no money. Here is how the system works. The passlock sensor and the ignition switch are in series. When you turn your key you generate a low current read by the body control module. If the current generated is out of range the BCM won't recognize the signal and your car won't start for 10 min. There could be different reasons why the signal is out of range. On most of the cases the ignition switch contacts are burned out, and this will cause a voltage drop on the contact so the signal getting to the BCM is going to be lower than usual so it will be out of range. Take your ignition switch out (if you don't know how send me your e-mail (believe me I'm not looking for e-mail addresses I just need to scan the instructions, since I have them only printed out) and I'll send you detailed instructions for free. Once the switch is out remove the cover on the back of the switch (it is clipped on, all you need is a flat head screwdriver). Once the cover is removed you should see 5 fairly big electric contacts. I bet at least one or two are burned out. Clean them with fine sand paper until their surface is clean and flat and make sure the steel springs pressing the contacts together are tight and are pushing the contacts firmly. If not, using pliers bend them to get good contacts. Reinstall the switch and your car should start every time. If the contacts are really bad you might have to change the ignition switch.
I know dealers want to change every part on the car so please do not let them change the passlock sensor. The passlock sensor is a hall sensor and there is no reason for the sensor to go bad.

Originally Posted by TerryOlson

1999 Silverado - Verify that we did he resistor bypass correctly please!

I found the three-wire connector to the passlock sensor on the ignition switch - one was yellow, another was black/orange stripe, and the last was red/white stripe.


We measured resistance per directions (stripped insulation from orange/black but did not cut it. We cut yellow - measuring from black/orange to yellow coming from the ignition switch). Found a resistance value of 3.5k ohms - and this reading was the same whether the ignition key was on or off. Not sure that should be the case?

My son started the truck AFTER we cut the black/orange wire and the yellow wire - not sure how or why it should even start like that but it ran as it should!

We cut the black/orange wire placing a 3.3k ohms resister between the black/orange leading to the ignition switch and the yellow leading to the BCM. Truck started but the security light remained on.

Reviewed instructions - not sure we were supposed to have cut the black/orange or just tap into it leaving it to continue to the switch. Reconnected it so it did this, tapping into that connection with the resistor, which we connected to yellow going to the BCM. All connections were soldered and insulated. Truck started and runs, but security light remains on.

Questions:

1) The resistance value that we found is within expected range according to many sources, but not all of them. Anyone know for sure?

2) I would expect that if the relearn was necessary to make this work the truck wouldn't have started at all and we would have had to complete this process. It starts and runs just fine - do we need to do the relearn to get the security light to go out?

I'm all kinds of confused...

Originally Posted by mobileinstaller

You should not have cut the reference ground wire just tapped into it. As to why it started with the wires cut not sure it should not have.

Originally Posted by TerryOlson

I cut the reference wire, then decided I shouldn't have and I soldered it back together and at that junction I also soldered one end of the resistor with the other end going to the yellow wire which goes to the BCM. Said another way, it was cut, but repaired such that it should be as you describe above - reference wire continuing to the ignition switch but with the resistor bridging from this to the BCM lead.

I'd think it would either not start and we should have to do the relearn process - or - start and run without tripping the security light. In our case it runs fine, but the security light still stays on.

I'm thinking the issue might have to do with something other than the passlock sensor - debris in the ignition switch, worn ignition switch, or poor connection quality somewhere which increases resistance beyond the acceptable range???

I've read elsewhere about cutting the BCM lead while the truck is running to bypass the system. If I understand correctly this will work just fine - until we lose power. Sooner or later I'll have to disconnect the battery for repair or replacement or it will go dead. If we go this route, how do we deal with that after power has been restored?

Thanks for any advice offered.

Originally Posted by TerryOlson

You're probably right. The resistance was the same whether the key was on or off. It seems to me that if the "wrong" resistance is encountered the truck won't start and I don't understand why it starts but the security light still comes on. Maybe there is that middle ground where it's close, but not enough that the light doesn't come on? Dunno.

Like I said, the damn thing started with the reference wire and also the BCM wire cut. I freaked when my son started it that way - worried that one of those would go to ground and fry something.

I'm not sure the relearn process works if the truck actually starts. We'll push through it just the same but I have my doubts about that. If I knew what I was talking about my doubts might mean something, but I do not!

Originally Posted by mobileinstaller

Like I said if you have the ability take the plastic around ignition harness off and take a couple pictures of where everything is and what you guys have done and I may be able to give youba better idea of what is going on. By the way is there anything imprinted on the metal portion of the key? Such as PK3 or plus sign with a circle around it.