EBCM or Lateral Accelerometer?
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Intermediate
Joined: May 2004
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From: King George VA
EBCM or Lateral Accelerometer?
Out driving my '02 unmoded Vert today when the left rear wheel momentarily locked up, throwing me slightly askew but easily recoverable since I was cruising only 35 MPH on a smooth, straight road. The DIC threw an immediate alert, "Service Active Handling".
When I got home I retrieved the following codes:
1. 28 TCS C1284H (Traction Control System) Lateral Accelerometer Sensor Bias Malfunction.
2. 28 TCS C1285H (Traction Control System) Lateral Accelerometer Sensor Circuit Malfunction.
These are the same codes I retrieved last week after the DIC threw the alert, "Service Active Handling" while driving on the Interstate. On the advice of Forum members, I cleared the codes and continued to drive the car to see if the Active Handling alert would appear again. After today's malfunction, I'm not sure it is safe to drive it until this problem is fixed since I do a lot of Interstate driving at 65-75 MPH.
I've searched the Forum but couldn't find any threads exactly on point. Most discuss AH's relationto the EBCM but since the above codes relate to the Lateral Accelerometer Sensor, I'm not sure the EBCM is the culprit.
Anyone have an experience like this? If so, what did you do? Anyone have any experience with these codes? If the problem is the LA Sensor, where is it located? How difficult is it to correct the malfunctions related to these codes? Are there any instructions available on the Forum to make the necessary corrections?
As always this Forum is the best! Again, any help will be appreciated.
When I got home I retrieved the following codes:
1. 28 TCS C1284H (Traction Control System) Lateral Accelerometer Sensor Bias Malfunction.
2. 28 TCS C1285H (Traction Control System) Lateral Accelerometer Sensor Circuit Malfunction.
These are the same codes I retrieved last week after the DIC threw the alert, "Service Active Handling" while driving on the Interstate. On the advice of Forum members, I cleared the codes and continued to drive the car to see if the Active Handling alert would appear again. After today's malfunction, I'm not sure it is safe to drive it until this problem is fixed since I do a lot of Interstate driving at 65-75 MPH.
I've searched the Forum but couldn't find any threads exactly on point. Most discuss AH's relationto the EBCM but since the above codes relate to the Lateral Accelerometer Sensor, I'm not sure the EBCM is the culprit.
Anyone have an experience like this? If so, what did you do? Anyone have any experience with these codes? If the problem is the LA Sensor, where is it located? How difficult is it to correct the malfunctions related to these codes? Are there any instructions available on the Forum to make the necessary corrections?
As always this Forum is the best! Again, any help will be appreciated.
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Thats an unusual snag and not one that gets posted very often.
Thinking about it and from the symptoms you describe it seems consistent with a problem with the lateral accelerometer. It seems that the car is sensing an error along the lateral axis and feeding in an opposite compensation. Once it does that you get the "twitch"
I'll take a look at the manual and see if theres anything in there that helps
I'd agree that it's a safety issue if you're getting undemanded inputs.
Thinking about it and from the symptoms you describe it seems consistent with a problem with the lateral accelerometer. It seems that the car is sensing an error along the lateral axis and feeding in an opposite compensation. Once it does that you get the "twitch"
I'll take a look at the manual and see if theres anything in there that helps
I'd agree that it's a safety issue if you're getting undemanded inputs.
Last edited by DeeGee; Feb 16, 2008 at 01:44 AM.
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
No other real advice from the manual. The diagnostic procedure needs a test set. The procedure involves checking voltages and making sure the harness conenctors are clean at the EBCM and at the lateral accelerometer. If all that fails they would replace the accelerometer or the EBCM
One thing though. Do you have any pull on the steering which might suggest the alignment is out? If so, that could cause the problem.
One thing though. Do you have any pull on the steering which might suggest the alignment is out? If so, that could cause the problem.
Last edited by DeeGee; Feb 16, 2008 at 01:21 AM.
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Just saw your other question
The lateral accelerometer sits on the passanger side of the center tunnel directly below the parking brake.
From the book: Removal Procedure
Turn ignition off
Remove the passanger seat (instructions on Vette Essentials site)
Disconnect the accelerometer connector
Remove the two lateral accelermeter nuts
Remove the lateral accelermeter
If thats the problem it should be easy to fix. Have to say, with those codes I'd check the connectors but I'd be tempted to do a change on spec if the part is reasonably cheap. Looks like the diagnostics could be expensive just in labor time. With those symptoms I'd say the accelerometer may well be the problem.
I'm no expert so others with more knowledge of the system may join in.
The lateral accelerometer sits on the passanger side of the center tunnel directly below the parking brake.
From the book: Removal Procedure
Turn ignition off
Remove the passanger seat (instructions on Vette Essentials site)
Disconnect the accelerometer connector
Remove the two lateral accelermeter nuts
Remove the lateral accelermeter
If thats the problem it should be easy to fix. Have to say, with those codes I'd check the connectors but I'd be tempted to do a change on spec if the part is reasonably cheap. Looks like the diagnostics could be expensive just in labor time. With those symptoms I'd say the accelerometer may well be the problem.
I'm no expert so others with more knowledge of the system may join in.
Last edited by DeeGee; Feb 16, 2008 at 01:33 AM.
Thread Starter
Intermediate
Joined: May 2004
Posts: 33
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From: King George VA
Thanks for your help, DeeGee. The car is well cared for and has 23k miles on it. It doesn't seem to have an alignment problem but that's a good item to check. It was last realigned at 12k miles. I've also checked the inflation pressures of the tires to ensure they were equal on the same axle and they were.
I started receiving the "Service Active Handling" alert intermitently last year. As others have experienced, the alert would be given only once in a while. The first time I got the alert was when I had pulled onto the gravel shoulder of a road for a short stop to retrieve something from the trunk. When I pulled back onto the road, the alert came on while the right tires were on gravel and the left tires were of course on pavement. I thought nothing of it because of the situation but the Active Handling light stayed on until I parked the car for the day. The light was off the next time I started it and had not received the alert for the longest time. The alert has been getting more frequent lately.
Also, thanks for the schematic of the LAS location and instructions on how to get to it. I'll check the connections and into the cost of that part and get back to you on it.
I'm also going to check the ABS sensors to see if they need cleaning. I can't think of anything else to check or replace at this time.
I started receiving the "Service Active Handling" alert intermitently last year. As others have experienced, the alert would be given only once in a while. The first time I got the alert was when I had pulled onto the gravel shoulder of a road for a short stop to retrieve something from the trunk. When I pulled back onto the road, the alert came on while the right tires were on gravel and the left tires were of course on pavement. I thought nothing of it because of the situation but the Active Handling light stayed on until I parked the car for the day. The light was off the next time I started it and had not received the alert for the longest time. The alert has been getting more frequent lately.
Also, thanks for the schematic of the LAS location and instructions on how to get to it. I'll check the connections and into the cost of that part and get back to you on it.
I'm also going to check the ABS sensors to see if they need cleaning. I can't think of anything else to check or replace at this time.
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Thanks for your help, DeeGee. The car is well cared for and has 23k miles on it. It doesn't seem to have an alignment problem but that's a good item to check. It was last realigned at 12k miles. I've also checked the inflation pressures of the tires to ensure they were equal on the same axle and they were.
I started receiving the "Service Active Handling" alert intermitently last year. As others have experienced, the alert would be given only once in a while. The first time I got the alert was when I had pulled onto the gravel shoulder of a road for a short stop to retrieve something from the trunk. When I pulled back onto the road, the alert came on while the right tires were on gravel and the left tires were of course on pavement. I thought nothing of it because of the situation but the Active Handling light stayed on until I parked the car for the day. The light was off the next time I started it and had not received the alert for the longest time. The alert has been getting more frequent lately.
Also, thanks for the schematic of the LAS location and instructions on how to get to it. I'll check the connections and into the cost of that part and get back to you on it.
I'm also going to check the ABS sensors to see if they need cleaning. I can't think of anything else to check or replace at this time.
I started receiving the "Service Active Handling" alert intermitently last year. As others have experienced, the alert would be given only once in a while. The first time I got the alert was when I had pulled onto the gravel shoulder of a road for a short stop to retrieve something from the trunk. When I pulled back onto the road, the alert came on while the right tires were on gravel and the left tires were of course on pavement. I thought nothing of it because of the situation but the Active Handling light stayed on until I parked the car for the day. The light was off the next time I started it and had not received the alert for the longest time. The alert has been getting more frequent lately.
Also, thanks for the schematic of the LAS location and instructions on how to get to it. I'll check the connections and into the cost of that part and get back to you on it.
I'm also going to check the ABS sensors to see if they need cleaning. I can't think of anything else to check or replace at this time.
