What I did with the Steering Column Lock
07-30-2011, 02:09 PM
#1
What I did with the Steering Column Lock
The Car:
2000 Corvette Hardtop
Steering column lock recall 01044 performed by dealer on 14 Aug 2001 (8500 miles).
Technician notes were “Replaced column lock relay and rewire per recall 01044.”
Parts used in recall were “26050960 Lock 2.195” and “88952428 Wire Kit 2.195”.
No other column lock recalls have been performed.
The Problem:
Everything was fine until roughly 67,500 miles when the message “Pull key, wait 10sec” appeared after I started the engine. I did what the message said, restarted, and everything was OK again. Three days later, I started the engine and got the “Pull key” message, did what it said, but this time it displayed “Service column lock”, the steering wheel was locked, and the engine died when the car started moving. In other words, the usual symptoms of the steering column lock failure that everyone is familiar with.
Diagnosing:
I checked the column lock relay in the passenger footwell above the Body Control Module. This was a 5-pin relay installed during the recall; the 2000 Corvette service manual shows a 4-pin as original equipment. With power supplied by a motorcycle battery and a 12v taillight lamp attached for load, the relay worked normally. Contact resistance was zero in both states, coil resistance was about 78 ohms. So the relay seemed OK.
Using the Column/Ignition Lock Schematic on page 2-54 of the 2000 service manual, I checked the circuits. Grounds were grounded, all continuities were good, fuse 23 was good, “hot at all times” were hot. So no faults found in the wiring.
I checked the 4-pin connector on the Steering Column Lock pigtail. Pin A – pin B (the motor position switch) was open. Pin D – pin C (the motor drive circuit) was a dead short. No pins were shorted to ground.
Although the above measurement suggested a short in the motor winding, I decided to try to unlock the steering by connecting a battery to pins D and C in the unlocking polarity. I expected to get lots of sparks as would be the case when shorting a battery, but in fact I saw only a very minor spark when first making contact and after that nothing happened. No sparks and the motor didn't make any noise (I was always able to hear it when it was working in the past). I reversed the polarity to the motor drive pins and again nothing happened. Checked resistance of pin D – pin C again and still a dead short.
The schematic on 2-54 shows a circuit breaker in series with the motor inside the Steering Column Lock, and the 2000 manual also states on page 8-378 that circuit breakers reset in “a few seconds” or “a second or two” depending on the type of circuit breaker. So I suspected that the reason there were no sparks when trying to drive the shorted motor was because the breaker opened almost instantaneously. Then by the time I rechecked pin D – pin C resistance the breaker had already reset so the circuit was closed again.
I repeated the test with the battery, this time with an ammeter attached, and the current initially went to about 5.5 amps, then after a second or two ramped down to nearly zero. Since the current decayed to zero instead of stepping down to zero in a single jump, I suppose this might be a PTC circuit breaker. Either that or my meter has really slow response.
Conclusion:
Root cause was probably an internal short in the column lock motor.
The Fix:
I decided that I wanted to remove the mechanical lock from the steering column. It's really annoying to think that there's a mechanism in there capable of locking the column and it isn't working properly anymore. Although the probability of having the column lock up while driving is very small, the consequences would be bad (think of oncoming traffic). So I was willing to do the extra work to remove the mechanical lock in addition to doing the usual column lock bypass electrical mod. I also wanted to leave all of the rotating components of the column unmodified if possible, so it looked like the best approach was to remove the steering column lock motor, lock pin, etc. from their housing and leave the lock plate on the column unchanged. Removing the steering column lock assembly entirely wouldn't really work because it also mounts the right side control stalk (wiper, etc.), but it's possible to gut all of the lock components and then reinstall the empty casting on the column.
There is other information on the forum and elsewhere that deals with the steering column disassembly process, so I won't go into details here. I just got the service tools (steering wheel puller with special legs, lock plate compressor, and steering lock pin) and followed the service manual procedure. Btw, there are a couple of mistakes in the manual. It recommends removing the steering column tilt head housing mechanism which is totally unnecessary; there's no need to go further than removing the turn signal cancel cam. It also says that there are 2 fasteners holding the column lock assembly to the column but there are actually 3.
After removing the column lock assembly from the car, I put it in a vise and used a cold chisel to knock off the retention pieces that secure the lock mechanism in the casting (which appears to be aluminum or zinc). Then it was possible to lift off the black plastic cover and remove the motor, geartrain, and lock pin. The position feedback switch is built in to the the black plastic cover. The photos show how the parts are arranged: the motor drives the worm, the worm drives the worm gear, the worm gear drives a power screw that moves the pin into the lock plate. The pin is spring loaded so if it's not aligned with a slot on the lock plate, the motor can still drive it to full travel and then when the steering wheel/lock plate is rotated the spring pushes the pin into engagement.
After all this, I was left with the bare casting whose only job now is to support the stalk. I installed it back on the column and reassembled everything else.
For the electrical/controls part of the problem, I installed a Column Lock Simulator from Thunder Racing to keep the body controller happy. This is also well documented elsewhere, like here: http://ls1howto.com/index.php?article=24
Then I removed the the 5-pin column lock relay that was installed during the recall and soldered together the wires on C1 (white) and A2 (orange) of the relay plug. Doing this eliminates the relay from the system (so a relay failure can't cause a fault in the future) while restoring the circuits between the body controller and the column lock bypass. This is electrically equivalent to the jumper described here:
http://forums.corvetteforum.com/c5-t...installed.html
I also wrapped the relay plug in electrical tape because there is one remaining orange wire in the plug (pin A1) that is “hot at all times” and I wanted to protect against shorts. This relay plug stays in the area that is at risk of getting wet if the A/C evaporator drain ever gets blocked, which happens to some of these cars from time to time.
The Result:
Everything seems to be back to normal. The car powered up normally at Key On, no more column lock message. Since no software changes were made, there's still a chance that a future problem in the steering column lock circuitry could set the “Service Column Lock” fault and shut off the engine when the car starts to move. For example, this could happen if the grounds degrade, or a problem develops in the wiring, or the Column Lock Simulator itself fails. If I ever get HPTuner or EFILive, I'll have to remember to change that fuel shutoff speed limit to prevent this from occurring.
Recall 01044:
I created a wiring diagram to show the circuits as they actually exist in my car. Compared to the 2000 service manual schematic, relay pins A2 and C1 were transposed, and relay pin B2 connects to BCM pin A6 and to Steering Column Lock pin C. It appears that the intent of recall 01044 was the following:
→ When the CL relay is de-energized, relay pins B2 and C1 short the lock motor, presumably to encourage it to stay in place.
→ When the CL relay is energized, BCM pin A8 connects to SCL pin D and BCM pin A6 connects to SCL pin C, which is the same circuit as was originally built.
So basically the recall 01044 system operates as the original system did except it adds the hold-in-place feature when the relay is de-energized. Or at least that's how it seems to me.
Here are some photos and wiring diagrams that show the important parts. Hopefully these will help people who want to understand how the system works; if nothing else, it's fun to see all the pieces.
Photo above shows 2 of the Steering Column Lock Assembly mounting screws immediately above and below the steering shaft. The third screw is not visible but is on the right side of the column.
2000 Corvette Hardtop
Steering column lock recall 01044 performed by dealer on 14 Aug 2001 (8500 miles).
Technician notes were “Replaced column lock relay and rewire per recall 01044.”
Parts used in recall were “26050960 Lock 2.195” and “88952428 Wire Kit 2.195”.
No other column lock recalls have been performed.
The Problem:
Everything was fine until roughly 67,500 miles when the message “Pull key, wait 10sec” appeared after I started the engine. I did what the message said, restarted, and everything was OK again. Three days later, I started the engine and got the “Pull key” message, did what it said, but this time it displayed “Service column lock”, the steering wheel was locked, and the engine died when the car started moving. In other words, the usual symptoms of the steering column lock failure that everyone is familiar with.
Diagnosing:
I checked the column lock relay in the passenger footwell above the Body Control Module. This was a 5-pin relay installed during the recall; the 2000 Corvette service manual shows a 4-pin as original equipment. With power supplied by a motorcycle battery and a 12v taillight lamp attached for load, the relay worked normally. Contact resistance was zero in both states, coil resistance was about 78 ohms. So the relay seemed OK.
Using the Column/Ignition Lock Schematic on page 2-54 of the 2000 service manual, I checked the circuits. Grounds were grounded, all continuities were good, fuse 23 was good, “hot at all times” were hot. So no faults found in the wiring.
I checked the 4-pin connector on the Steering Column Lock pigtail. Pin A – pin B (the motor position switch) was open. Pin D – pin C (the motor drive circuit) was a dead short. No pins were shorted to ground.
Although the above measurement suggested a short in the motor winding, I decided to try to unlock the steering by connecting a battery to pins D and C in the unlocking polarity. I expected to get lots of sparks as would be the case when shorting a battery, but in fact I saw only a very minor spark when first making contact and after that nothing happened. No sparks and the motor didn't make any noise (I was always able to hear it when it was working in the past). I reversed the polarity to the motor drive pins and again nothing happened. Checked resistance of pin D – pin C again and still a dead short.
The schematic on 2-54 shows a circuit breaker in series with the motor inside the Steering Column Lock, and the 2000 manual also states on page 8-378 that circuit breakers reset in “a few seconds” or “a second or two” depending on the type of circuit breaker. So I suspected that the reason there were no sparks when trying to drive the shorted motor was because the breaker opened almost instantaneously. Then by the time I rechecked pin D – pin C resistance the breaker had already reset so the circuit was closed again.
I repeated the test with the battery, this time with an ammeter attached, and the current initially went to about 5.5 amps, then after a second or two ramped down to nearly zero. Since the current decayed to zero instead of stepping down to zero in a single jump, I suppose this might be a PTC circuit breaker. Either that or my meter has really slow response.
Conclusion:
Root cause was probably an internal short in the column lock motor.
The Fix:
I decided that I wanted to remove the mechanical lock from the steering column. It's really annoying to think that there's a mechanism in there capable of locking the column and it isn't working properly anymore. Although the probability of having the column lock up while driving is very small, the consequences would be bad (think of oncoming traffic). So I was willing to do the extra work to remove the mechanical lock in addition to doing the usual column lock bypass electrical mod. I also wanted to leave all of the rotating components of the column unmodified if possible, so it looked like the best approach was to remove the steering column lock motor, lock pin, etc. from their housing and leave the lock plate on the column unchanged. Removing the steering column lock assembly entirely wouldn't really work because it also mounts the right side control stalk (wiper, etc.), but it's possible to gut all of the lock components and then reinstall the empty casting on the column.
There is other information on the forum and elsewhere that deals with the steering column disassembly process, so I won't go into details here. I just got the service tools (steering wheel puller with special legs, lock plate compressor, and steering lock pin) and followed the service manual procedure. Btw, there are a couple of mistakes in the manual. It recommends removing the steering column tilt head housing mechanism which is totally unnecessary; there's no need to go further than removing the turn signal cancel cam. It also says that there are 2 fasteners holding the column lock assembly to the column but there are actually 3.
After removing the column lock assembly from the car, I put it in a vise and used a cold chisel to knock off the retention pieces that secure the lock mechanism in the casting (which appears to be aluminum or zinc). Then it was possible to lift off the black plastic cover and remove the motor, geartrain, and lock pin. The position feedback switch is built in to the the black plastic cover. The photos show how the parts are arranged: the motor drives the worm, the worm drives the worm gear, the worm gear drives a power screw that moves the pin into the lock plate. The pin is spring loaded so if it's not aligned with a slot on the lock plate, the motor can still drive it to full travel and then when the steering wheel/lock plate is rotated the spring pushes the pin into engagement.
After all this, I was left with the bare casting whose only job now is to support the stalk. I installed it back on the column and reassembled everything else.
For the electrical/controls part of the problem, I installed a Column Lock Simulator from Thunder Racing to keep the body controller happy. This is also well documented elsewhere, like here: http://ls1howto.com/index.php?article=24
Then I removed the the 5-pin column lock relay that was installed during the recall and soldered together the wires on C1 (white) and A2 (orange) of the relay plug. Doing this eliminates the relay from the system (so a relay failure can't cause a fault in the future) while restoring the circuits between the body controller and the column lock bypass. This is electrically equivalent to the jumper described here:
http://forums.corvetteforum.com/c5-t...installed.html
I also wrapped the relay plug in electrical tape because there is one remaining orange wire in the plug (pin A1) that is “hot at all times” and I wanted to protect against shorts. This relay plug stays in the area that is at risk of getting wet if the A/C evaporator drain ever gets blocked, which happens to some of these cars from time to time.
The Result:
Everything seems to be back to normal. The car powered up normally at Key On, no more column lock message. Since no software changes were made, there's still a chance that a future problem in the steering column lock circuitry could set the “Service Column Lock” fault and shut off the engine when the car starts to move. For example, this could happen if the grounds degrade, or a problem develops in the wiring, or the Column Lock Simulator itself fails. If I ever get HPTuner or EFILive, I'll have to remember to change that fuel shutoff speed limit to prevent this from occurring.
Recall 01044:
I created a wiring diagram to show the circuits as they actually exist in my car. Compared to the 2000 service manual schematic, relay pins A2 and C1 were transposed, and relay pin B2 connects to BCM pin A6 and to Steering Column Lock pin C. It appears that the intent of recall 01044 was the following:
→ When the CL relay is de-energized, relay pins B2 and C1 short the lock motor, presumably to encourage it to stay in place.
→ When the CL relay is energized, BCM pin A8 connects to SCL pin D and BCM pin A6 connects to SCL pin C, which is the same circuit as was originally built.
So basically the recall 01044 system operates as the original system did except it adds the hold-in-place feature when the relay is de-energized. Or at least that's how it seems to me.
Here are some photos and wiring diagrams that show the important parts. Hopefully these will help people who want to understand how the system works; if nothing else, it's fun to see all the pieces.
Photo above shows 2 of the Steering Column Lock Assembly mounting screws immediately above and below the steering shaft. The third screw is not visible but is on the right side of the column.
The following 3 users liked this post by Paris Hilton's Dog:
07-30-2011, 02:34 PM
#2
Very interesting post! And thank you for the fine pictures of the locking mechanism, something I have of course read much about on the Forum but have not seen clearly until now.
I often daydream about how nice a C5 would be if it had been built with all the government-mandated crap left out, along with unnecessarily-complex electronic and mechanical items such as that wretched column lock. Car would probably weigh hundreds of pounds less, drive nicer, and go faster.
Thanks again!
I often daydream about how nice a C5 would be if it had been built with all the government-mandated crap left out, along with unnecessarily-complex electronic and mechanical items such as that wretched column lock. Car would probably weigh hundreds of pounds less, drive nicer, and go faster.
Thanks again!
The following users liked this post:
CorvetteBrent (07-10-2018)
07-31-2011, 02:11 PM
#4
Team Owner
What I did was this.....
In "Paris Hilton's" last picture, you see the backside of the "lockplate", the round part with the "detents" that engage the "lockpin". I took my lockplate, chucked it in a lathe, and removed all the material from the inner ridge out, removing all the detents.
No, my column won't lock and help deter theft, but on the other hand, I won't be stranded by the side of the road, either...
The following 2 users liked this post by leadfoot4:
Black 03 Z06 (07-10-2018),
CorvetteBrent (07-10-2018)
07-31-2011, 03:51 PM
#5
Advanced
Member Since: Nov 2009
Location: Fort Worth TX
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
I had the service column lock issue when my battery was starting to fail. I replaced the battery, still had the light. Got a tuner to set the shut off speed to 255 mph. The car already had the k-harness recall and the ring to not allow the column to lock anymore. The problem ended up being a bad k-harness under the knee bolster. I had to unplug the K-harness and plug it back in the way it came from factory and problem was fixed. Hope that helps anyone else that is having this problem.
03-31-2013, 08:51 PM
#7
I decided not to remove the lock plate because of concern over the possibility that it may have other (perhaps non-obvious) functions, such as controlling the axial positions of other components on the steering column.
Hacksawing the lock pin off would be possible but actually it might not be much less work than what was shown above.
The following users liked this post:
CorvetteBrent (07-10-2018)
03-31-2013, 09:24 PM
#8
Chevy has a replacement plate that doesn't have the holes and smaller diameter. I found the easiest was to cut the pin off. You don't even have to remove the steering wheel. I cut about 2\3rds through then grabbed the steering wheel and gave a quick jerk and the rest snapped right off.
The following users liked this post:
CorvetteBrent (07-10-2018)
04-04-2013, 04:08 PM
#9
Le Mans Master
The GM recall kit comes with a smaller plate that also cancels the turn signal... One forum member removed the lockplate, and took the time to grind it down so all the locking holes were gone, then re-used what was left of the original plate...
I removed the lockplate and installed the GM relay, and it is still working fine... Once the lockplate is removed, there is nothing to put the pin in a bind.
I removed the lockplate and installed the GM relay, and it is still working fine... Once the lockplate is removed, there is nothing to put the pin in a bind.
The following users liked this post:
CorvetteBrent (07-10-2018)
04-04-2013, 04:25 PM
#10
Le Mans Master
Great write up! I solved the lock issue by making a "L" shaped piece and used JB Weld to cement it in place to hold the locking rod down and block it from ever extending into the locking plate. 15 minutes and then waited overnight for it to cure. FIXED! Then programmed out the 2mph kill feature with my HPTuner.
The following users liked this post:
CorvetteBrent (07-10-2018)
04-04-2013, 04:39 PM
#11
The following users liked this post:
CorvetteBrent (07-10-2018)
10-15-2017, 12:56 PM
#13
Le Mans Master
Very cool to come back and reload the pics for those that may benefit.
10-15-2017, 02:42 PM
#14
Team Owner
10-18-2017, 08:26 PM
#15
Burning Brakes
Am I correct in my understanding that later C5s (e.g.: my 04) don't have the steering column lock? When I turn off my key I hear a motor sound in the steering column, but my steering wheel doesn't lock.
10-25-2017, 12:44 PM
#19
Burning Brakes
My 04 has had the CLB pictured since 2007. I also have had a tune done to the car that among other things set the 2mph fuel shutoff to 255mph. I will not be changing a thing even though I am an big fan of the LMC5 for those that have never done anything. The LMC5 has 2 advantages over the CLB. First it is solid state rather than relay based so it may be much more reliable. Second the LMC5 is installed right at the BCM so it basically abandons all factory and recall wiring down stream of the BCM that was done on the column lock system. This means it is far easier to install and will not be subject to any factory or recall components that might fail over time.
Reason I ask is because I'm digging through my HPTuners file and I don't see a fuel shutoff that seems associated with a steering wheel lock function. All I see it the main cutoff RPM vs. Gear (used for standard rev limiter).
10-25-2017, 01:30 PM
#20
Burning Brakes
Used to be under Security as I recall.
There was a heading of Column Lock with an enable and disable option. Select disable and change the shutoff number from 2 to a high value like 250 or 255. This was MANY years back on a probably much older than the current version of HP Tuners. Perhaps back as far as 2008.
There was a heading of Column Lock with an enable and disable option. Select disable and change the shutoff number from 2 to a high value like 250 or 255. This was MANY years back on a probably much older than the current version of HP Tuners. Perhaps back as far as 2008.
Turns out I had already turned it off (set to "Not Fitted) when I first purchased the car and then forgot about it
Last edited by ChrisLSx; 10-25-2017 at 01:30 PM.