C1296 ... and rain
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
C1296 ... and rain
Back story; my car displays the "Service Active Handling" message in spurts. It did so last year about once every 1-2 days for a week or so. Then nothing for some time (I think the year).
Earlier this year it did similar, then gone.
This week... every day (my Z is my DD). Today it rained, plenty. On my drive home I could not even reset it for one second without immediately setting off the ding ding again, the full way home.
I'll see what happens in the morning (car is in garage overnight).
Initial questions:
Anybody think the rain/humidity could cause the sudden full on issue?
This is a brake issue yes? Brake sensor? How do I narrow it down to the exact problem?
Earlier this year it did similar, then gone.
This week... every day (my Z is my DD). Today it rained, plenty. On my drive home I could not even reset it for one second without immediately setting off the ding ding again, the full way home.
I'll see what happens in the morning (car is in garage overnight).
Initial questions:
Anybody think the rain/humidity could cause the sudden full on issue?
This is a brake issue yes? Brake sensor? How do I narrow it down to the exact problem?
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Add... prior to this afternoon it usually seemed to occur sitting at a light when my foot is off the brake (most of my trip home is flat). Also, today was the first rainy day.
Tech Contributor
Joined: Oct 1999
Posts: 41,036
Likes: 9,798
From: Charlotte, NC (formerly Endicott, NY)
What year car? Pre 2001 cars used a brake pressure sensor located on the master cylinder, 2001 and newer cars used a brake pressure sensor located on the brake pressure modulator valve. I attached a pdf that covers both the early and late implementations. If the brake pressure sensor needs to be replaced in the early system you work with the combination valve at the master cylinder if it needs to be replaced in the later systems you will need to replace the BPMV.
Bill
Bill
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Hot damn, I go out for a while and great answers already! Yes, it's an 04Z.
I have a friend who I'm pretty sure has the Tech II, will look into that to start.
It'll be interesting to see what the morning commute brings.
I have a friend who I'm pretty sure has the Tech II, will look into that to start.
It'll be interesting to see what the morning commute brings.
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
DTC C1296 is a problem with the voltage at the Brake Fluid Pressure Sensor on the EBCM. The voltages are out of range (ie less than 0.14V or greater than 4.9V). The sensor in question is used to "provide more accurate braking control during VSES." VSES is GM's collective term that describes Traction Control and/or Active Handling. VSES = Vehicle Stability Enhancment Services. When the code is set the ABS function remains operational but both AH and TC are disabled and appropriate lights are illuminated on the dash and messages are displayed in the DIC.
Problem can be with the wiring to the sensor (including the connector on the sensor) or the sensor itself may be bad. You may be able to use a digital multi meter to do the diagnostic testing but it would be far easier if you had a Tech II scan tool. I can post the diagnostic tree from the 04 shop manual if you want it. But it assumes the diagnosis is being done using a Tech II.
Problem can be with the wiring to the sensor (including the connector on the sensor) or the sensor itself may be bad. You may be able to use a digital multi meter to do the diagnostic testing but it would be far easier if you had a Tech II scan tool. I can post the diagnostic tree from the 04 shop manual if you want it. But it assumes the diagnosis is being done using a Tech II.
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Follow up. I wiggled then pushed both wiring harnesses towards the BPMV the night of my last post. Perhaps it was just a poor connection, or just a return to sporadic issues (in other words it'll surface again in half a year). Whatever it is, I drove it all last week (15 runs), not one warning.
I'll obviously hold on to this for if and when it pops up again. Thanks guys for now!
I'll obviously hold on to this for if and when it pops up again. Thanks guys for now!
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Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
NP, most of us need results at one point or another. If it happens again I'll somehow remove, check cleanliness and plug in. All connections are after all in a 14 year old car in an engine compartment.
Thread Starter
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
This thing is a PITA. I don't get it for weeks or months, then can't not get it for a few drives.
If this helps solve it, it only happens when the car hits operating temperature. And if it does happen, it does so the instant it hits temp. Does the computer only run these checks after warming up?
It's so consistent that I know what block (+/- a block max) it'll chime in on the way to work or home (when it decides to do so).
I know, take the time to do the measuring per above. I eventually will, just busy, life getting in the way. Chances are it'll be a winter project. Take my 7 and 4 year old girls out to help me.
If this helps solve it, it only happens when the car hits operating temperature. And if it does happen, it does so the instant it hits temp. Does the computer only run these checks after warming up?
It's so consistent that I know what block (+/- a block max) it'll chime in on the way to work or home (when it decides to do so).
I know, take the time to do the measuring per above. I eventually will, just busy, life getting in the way. Chances are it'll be a winter project. Take my 7 and 4 year old girls out to help me.
Tech Contributor
Joined: Oct 1999
Posts: 41,036
Likes: 9,798
From: Charlotte, NC (formerly Endicott, NY)
This thing is a PITA. I don't get it for weeks or months, then can't not get it for a few drives.
If this helps solve it, it only happens when the car hits operating temperature. And if it does happen, it does so the instant it hits temp. Does the computer only run these checks after warming up?
It's so consistent that I know what block (+/- a block max) it'll chime in on the way to work or home (when it decides to do so).
I know, take the time to do the measuring per above. I eventually will, just busy, life getting in the way. Chances are it'll be a winter project. Take my 7 and 4 year old girls out to help me.
If this helps solve it, it only happens when the car hits operating temperature. And if it does happen, it does so the instant it hits temp. Does the computer only run these checks after warming up?
It's so consistent that I know what block (+/- a block max) it'll chime in on the way to work or home (when it decides to do so).
I know, take the time to do the measuring per above. I eventually will, just busy, life getting in the way. Chances are it'll be a winter project. Take my 7 and 4 year old girls out to help me.
By the way ABS self diagnostics are run when you hear that brrrp noise just after the car gets up to about 6 mph. Sometimes it may travel a couple hundred feet before it kicks in the diagnostic.
Bill
Last edited by Bill Dearborn; Aug 24, 2018 at 08:04 PM.