99 C5...I give up

8224 Views 37 Replies 5 Participants Last post by Norm 1, 11 d ago

bootleggerjim

Discussion Starter · Mar 14, 2021

Pull key 10 second and steering column lock deal....auto trans, motor starts and dies.....install LCM machine....the car will start and run only if I connect ground side battery after 1 minute.....switch it off and column lock back and motor dies....do the battery deal and runs......new battery...I'm lost....If anyone can help, please....been working on this thing for 3 months....did the brown wire deal, did the cut the loop wire deal.....

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autowiz

· #2 · Mar 16, 2021

Hello. It sounds like you are having a problem with your column lock on your C5. I read your list of symptoms and things you have tried but see absolutely no mention of a trouble code pulled from your BCM(Body Control Module). So you know there are actually a handful of things that can fail and create the problem you are having and that is why todays cars store Diagnostic Trouble Codes(DTC's). On your 1960's C2 if you weren't getting fuel it was likely a carb or a fuel pump or rotten lines. And that is pretty much all that there is on such a mechanical thing. On your C5 there could be hundreds or more possible things that might be creating your no fueling condition. And in truth your C5 can store any one of THOUSANDS of diagnostic trouble codes to point you off in the right direction of the circuit or component you need to be testing to find the right repair. I think you would have better odds with the lottery than trying to make a diagnostic call and repair on todays cars without looking at the data stored in the controllers first.

From my experiences the BCM mounts on the passenger toe board right next to the fuse box. This BCM fails regularly when it gets wet. Also there is a relay just above the BCM that powers the column lock relay and it loves to fail. The 'fix' bypass you have applied is not some kind of magic cure all for every single problem a column lock could have. OMG, if only, right? That bypass is for when the motor itself on the column has failed. But this bypass requires the rest of the circuit to be functioning properly and I'm pretty sure your diagnosis to this point has told us all there is absolutely nothing wrong with your column lock assembly and you are having a problem with it's driving circuit. To correctly pinpoint and fix this problem you first need to pull trouble codes out of your BCM. Then once you have your trouble code you will need a shop database like 'ShopkeyPro' to give you a trouble tree and a wiring diagram so you can accurately pinpoint your problem. And then if it be a bad BCM you will need to have it at the dealer to have it programmed to the vehicle. This is an excellent problem for you to pay a professional to resolve for you.

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bootleggerjim

Discussion Starter · #3 · Mar 16, 2021

autowiz said:
Hello. It sounds like you are having a problem with your column lock on your C5. I read your list of symptoms and things you have tried but see absolutely no mention of a trouble code pulled from your BCM(Body Control Module). So you know there are actually a handful of things that can fail and create the problem you are having and that is why todays cars store Diagnostic Trouble Codes(DTC's). On your 1960's C2 if you weren't getting fuel it was likely a carb or a fuel pump or rotten lines. And that is pretty much all that there is on such a mechanical thing. On your C5 there could be hundreds or more possible things that might be creating your no fueling condition. And in truth your C5 can store any one of THOUSANDS of diagnostic trouble codes to point you off in the right direction of the circuit or component you need to be testing to find the right repair. I think you would have better odds with the lottery than trying to make a diagnostic call and repair on todays cars without looking at the data stored in the controllers first.

From my experiences the BCM mounts on the passenger toe board right next to the fuse box. This BCM fails regularly when it gets wet. Also there is a relay just above the BCM that powers the column lock relay and it loves to fail. The 'fix' bypass you have applied is not some kind of magic cure all for every single problem a column lock could have. OMG, if only, right? That bypass is for when the motor itself on the column has failed. But this bypass requires the rest of the circuit to be functioning properly and I'm pretty sure your diagnosis to this point has told us all there is absolutely nothing wrong with your column lock assembly and you are having a problem with it's driving circuit. To correctly pinpoint and fix this problem you first need to pull trouble codes out of your BCM. Then once you have your trouble code you will need a shop database like 'ShopkeyPro' to give you a trouble tree and a wiring diagram so you can accurately pinpoint your problem. And then if it be a bad BCM you will need to have it at the dealer to have it programmed to the vehicle. This is an excellent problem for you to pay a professional to resolve for you.

My only codes are 2587 H....& 2721 H.......my steering wheel has never locked in the 6 years I've had the car.....it has been wet in the p/s floor, I've pulled and inspected the BCM board and no signs of water damage there....I also retrained the Vats key a few times.....I don't have access to a ShopeyPro, also the GM dealer here is no help as they tell me GHM has pulled all info on 99 and back cars....my poor car has been down 4 months.....thank you for the info.....jim

autowiz

· #4 · Mar 17, 2021 (Edited)

So your B2721 code is for the Pass-Key detection circuit being out of rang and this is likely the result of broken wires that lead away from the lock and tumbler half of your ignition switch. This problem will keep the BCM from being able to read the resistance value in that pellet in the center of your key. This can be easily verified with a high end/dealer level scantool looking at the data stream in the bcm while inserting and turning the key. Your B2587 code is your Column lock/unlock drive 'A' open or short to ground. This code is telling you the column lock system has lost it's power feed and of course you wont have any operation if the motor never sees +12V from anywhere. This problem MIGHT be the electrical half of the ignition switch, or MAYBE it is fuse #23 in the toe board fuse box, or there is a CHANCE it is the column lock relay which mounts in the toe board just above the BCM and has 2 orange wires a green and a white wire going to it, or you could get real LUCKY and have it be an expanded pin in any one of the connectors in between. Any of these failures are common. If I were you and you know you need one half of the ignition switch I would go ahead and change both. Get the lock and tumbler and get the electrical half of the ignition switch. You will have to change the gates and springs from your old tumbler to the new one as you must keep the same key. And then you can re assess the column lock deal. If there were still problems with that after fixing the ignition switch you might try changing that relay next making sure you are carefully investigating the pins in the connectors of the components you are changing.

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bootleggerjim

Discussion Starter · #5 · Mar 17, 2021

I installed a new ing switch, and checked the key reader at the plug end, its reading the key....fuse #23 is good....I also installed a LMC that did away with the relay...I'l try the relay thing today and check for bad wire from key plug to BCM.....I also Detoxed all pins and checked for water damage, all looked OK.....thank you for helping me...I'm sure I'm missing something.....

autowiz

· #6 · Mar 17, 2021 (Edited)

I'm lost at doing away with that relay? What do you mean by LMC? Are you referring to the bypass for the motor under the column? Or are you saying you have something else other than a relay plugged into the relay socket above the BCM?

bootleggerjim

Discussion Starter · #7 · Mar 17, 2021

Compliance parts makes a module called LMC5. that fixes the column lock stuff....it has very good revues....when you install it on the BCM, you take the column lock relay out....

autowiz

· #8 · Mar 18, 2021 (Edited)

I don't think I like that LMC5 too much buddy. Any new product today is gonna be released with a bunch of positive reviews from friends or even paid for as a boost to a new business or product. That is just how this here internet works. But the reviews that say the pull key wait message came back and they wouldn't respond to emails is pretty telling. Honestly if this were to be done in a shop setting it would go to a B level tech. Just because it involves depinning and repinning major harness connectors. That is not a job for the average joe. Even if you could do it you likely do not understand going in what I am explaining to you now about even reaching a diagnosis before butchering a harness. You know because the first handful of times you try to depin a connector you might hurt the pins in such a way they will not make a tight connection to their mating pin anymore or just push back out of the cavity as you go to seat the connector. And you likely do not have access to a wiring diagram of the BCM and what all those pins and cavities go to or where they are supposed to go at any rate. And by the way B2587 requires power to be missing for just 100ms which puts this problem firmly in the possibility of being a poor connection. Anyways that is my rant on the 'LMC5'. The best I can recommend to you for that is to watch a tutorial on its install and make darn sure all your pins are in their correct cavities. Here is one video I found:

(1) LMC5 Module Installation on C5 Corvette - YouTube

I have personally installed a large number of these guys right here: Corvette Column Lock Bypass : 1997-2004 C5| WestCoastCorvette.com . This one just plugs in to the little 4 pin connector directly underneath the steering column. And that is it. Of course when we install this we have already run a complete diagnostic routine that has led us to a failed motor and a customer that doesn't want to pay to tear down the column to replace it. If your car came to me in the way it sits right now I would put your car back together the factory way, verify the failure, and begin a diagnostic by finding and following a trouble tree that applies to the symptoms I just comfirmed and the codes in the BCM.

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autowiz

· #9 · Mar 18, 2021 (Edited)

Ok I have taken the time to draw you a diagram of how the column lock motor gets wired to the relay and the BCM with nothing else in the way to distract. This should give you a better picture of how the circuit is operating.

The code is for the wire that passes through the relay going to the motor. If the relay coil can't close the contacts then the ckt will stay open and there will be no operation. The relay coil can go open or short, the moving parts within it can fail. I don't have an answer for how you would get this code in your current wired configuration.

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bootleggerjim

Discussion Starter · #10 · Mar 18, 2021

autowiz said:
Ok I have taken the time to draw you a diagram of how the column lock motor gets wired to the relay and the BCM with nothing else in the way to distract. This should give you a better picture of how the circuit is operating.

The code is for the wire that passes through the relay going to the motor. If the relay coil can't close the contacts then the ckt will stay open and there will be no operation. The relay coil can go open or short, the moving parts within it can fail. I don't have an answer for how you would get this code in your current wired configuration.

So the key code goes through fuse 23 to the relay, and D14 and A8 ,to the BCM, on through the lock motor and then A6 to BCM.......and C15 ti ground....does that sound right.....? again thanks for taking time to help and old Hot Rodder......

autowiz

· #11 · Mar 18, 2021

This circuit is for the column lock and has little to do with the pass-key problem that is creating your b2721 code. For the B2587 battery power comes in from fuse 23. this power feeds the control side of the relay and the bcm provides the gound and when the coil in the relay is energized the circuit to the motor is completed and the bcm can change states on demand. The pass-key can be from broken angel hair wires leading away from the tumbler in the ignition switch or it can be from a dirty key pellet or it can be from poor connections between the ignition switch and bcm for those angel hair wires or it can even be from somebody trying to improperly relearn the key code by leaving the ignition on 3 times for 10 minutes. So let me ask you this, did you try to relearn your key to the bcm while there was an active problem with this circuit??

autowiz

· #12 · Mar 18, 2021 (Edited)

The B2721 code sets because the BCM can not read the pellet in your key.

The B2587 code sets because when the BCM commands the column lock relay to close there is still an open loop in the motor circuit.

These are 2 different problems that you have happening that while both can bring up your pull key wait 10 sec message they are completely different problems that need to be addressed separately. Both of the angel hair wires that read that pellet go directly to the BCM. Because the pellet in the key is just a resistor and the circuit in the BCM is just an ohm meter carefully measuring the resistance of that circuit so it knows the 'code' which is the resistance of the 'pellet' which is just a resistor. I would go after this problem first if it were my car or customer. Then once I knew I had no vats problems I would diagnose and correct that column lock problem.

bootleggerjim

Discussion Starter · #13 · Mar 18, 2021

I'm an old Nitro Fuel car guy, I could help you tune your Nitro car and make big power.....this BCM stuff is not much fun for me....I did check my keys and the switch that reads the key at the 2 prong plug under the dash....its reading the key fine at the plug...after that I'm not sure....also I did relearn the key and after it would start and keep running...but after turning the car off, same old message and start and off again....having bad weather today so tomorrow I will remove the LMC and put everything back and start over....

Wheel Tire Land vehicle Vehicle Car

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autowiz

· #14 · Mar 19, 2021

That relay that you removed and replaced is known to fail. You can test this relay by applying power and ground to the 2 sides of the coil at pins 85 & 86 of the relay and making sure the contacts at pins 30 and 87 of the relay close. I test relays all the time in my life and I do it with a miltimeter set to ohms probing pins 30 and 87 and then i use a Power Probe iv to apply ground and send power to pins 85 & 86. The Power Probe iv is an intelligent test light that has miltimeter functions built in. Aside from sending power or ground and measuring these voltages this can also look at frequencies and duty cycles. So we can probe a fuel injector driver or an IAC or other PWM circuit and see what it is doing. They have been out for a while now and are coming down in price. You can get one on Amazon here: Amazon.com: Power Probe IV w/Case & Acc - Red (PP401AS) [Car Diagnostic Test Tool Digital Volt Meter ACDC Current Resistance Circuit Tester Fuel Injector Tester]: Automotive

bootleggerjim

Discussion Starter · #15 · Mar 19, 2021

Wow....cool tool, I'll have to get one...I'll test the relay in a few minutes.....thanks again too, you are a great guy helping me out......I'll get back soon...

bootleggerjim

Discussion Starter · #16 · Mar 19, 2021

OK, removed the LMC and put back all wires, installed a new relay......pull key 10 second deal, steering column lock deal, motor runs for about 10 seconds and shots off......new battery too....

bootleggerjim

Discussion Starter · #17 · Mar 19, 2021

2 new codes now....2587 H. and 2592 H

autowiz

· #18 · Mar 19, 2021

So both of those codes are for the same thing. One is for column lock drive A open or short and the other is column lock drive B open or short. These are the 2 wires that go from the bcm to the motor and to the relay. If your relay is failed it will not complete this circuit and them codes are what you will get. This might be a bad relay. The pins in the connector for the relay should be clean and not expanded. And the same with the pins at the BCM connector. These tests are critical for you right now because if these circuits all check out the next step is to replace the controller. The BCM. And it will need to be programmed to the vehicle by a dealer so you really want to be accurate in your circuit testing. Also you can look at the small square 4p connector under the steering column for the motor itself. If these pins got hot and expanded this alone might be your problem. Test the relay and see if it is bad. energize pin 85 while grounding pin 86 or vice versa and listen for a clicking sound.

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bootleggerjim

Discussion Starter · #19 · Mar 19, 2021

I checked the 4p under dash, looks very good.....the relay I replaced above the BCM was bad....new relay is clicking.....also I checked the key reader at the BCM and its reading there.....

autowiz

· #20 · Mar 20, 2021

So clear the codes and what codes reset or did the relay fix your problems?

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