wiring help - yaw rate sensor

[aboturky839]

hi hope you are okay



i have a problem in my car in the yaw rate sensor under the passenger seat there is not power to the green wire that must have 5v power when i test it i
it game 0.200 volt what could be the problem please help i need to fix it today

trailblazer 2007 LT

 

[CaptainXL]

hi hope you are okay



i have a problem in my car in the yaw rate sensor under the passenger seat there is not power to the green wire that must have 5v power when i test it i
it game 0.200 volt what could be the problem please help i need to fix it today

trailblazer 2007 LT

Must be for the stabilitrak system. Check the fuse?

 

[jimmyjam]

it comes from the Steering wheels Speed Position Sensor (pin 1/grey)

to the brake module (pin 25/grey)

out the brake module (pin 23/dark green)

to the yaw sensor

 

[IllogicTC]

it appears that comes from the Steering Wheel Position Sensor.

EDIT
Sorry, it comes from the EBCM

Nope. The SWPS would not provide a constant +5V. It may be tied to the same regulator that provides the reference voltage for the SWPS though.

It comes from the Electronic Brake Control Module (EBCM), located on the inner left frame rail, beside the transmission. The wire runs from Pin 23 on the connector down there to the yaw sensor.

 

[jimmyjam]

there's a voltage regulator in the steering wheel sensor

 

[aboturky839]

so where is the voltage regulater found so i could change it

 

[aboturky839]

hi hope you are okay



i have a problem in my car in the yaw rate sensor under the passenger seat there is not power to the green wire that must have 5v power when i test it i
it game 0.200 volt what could be the problem and where is the voltage regulater found View attachment 33204

trailblazer 2007 LT

 

[IllogicTC]

hi hope you are okay



i have a problem in my car in the yaw rate sensor under the passenger seat there is not power to the green wire that must have 5v power when i test it i
it game 0.200 volt what could be the problem and where is the voltage regulater found View attachment 20656

trailblazer 2007 LT

The regulator is an integrated part of the ECBM. You may have to take it to a dealership or another place with a high-end scan tool to have body/chassis codes read, the system may have detected a failure in the module but not something which would turn on the check engine light.

Refer to my previous post on where to find the ECBM. You can test voltage there at the source, if you're only getting 0.2 volts there too you may have to replace the module.

 

[aboturky839]

The regulator is an integrated part of the ECBM. You may have to take it to a dealership or another place with a high-end scan tool to have body/chassis codes read, the system may have detected a failure in the module but not something which would turn on the check engine light.

Refer to my previous post on where to find the ECBM. You can test voltage there at the source, if you're only getting 0.2 volts there too you may have to replace the module.

actually i got it to a dealership and they had another EBCM that they tested on the truck but it didnot work even so what should i do, what wire should i test from the EBCM ?

 

[aboturky839]

also i have my coil spring not working but the wheel speed sensor is working ????

 

[jimmyjam]

The picture I posted clearly shows there is a regulator in the wheel position sensor. Don't know where illogicTC is getting his info from.

the clock spring has nothing to do with the position sensor

 

[aboturky839]

ok but in the computer scan for the speed wheel sensor it is working good ?? still dont know what to do also my abs light is on after wheel hub change for both front tires

 

[jimmyjam]

1. Look at the diagram...

2. Test Pin 25 GRAY and Pin 23 DARK GREEN on the EBCM, VDC when its plugged in to the ebcm and not, key in run...

3. ???

4. profit!

does pin 25 and pin 23 show <1V when plugged in? does pin23 show 0V when unplugged and pin 25 still show voltage?

 

[IllogicTC]

The picture I posted clearly shows there is a regulator in the wheel position sensor. Don't know where illogicTC is getting his info from.

the clock spring has nothing to do with the position sensor

From the diagrams in the shop manual set

 

[jimmyjam]

From the diagrams in the shop manual set

care to share?

 

[aboturky839]

how can i test the two pins is it from the yaw rate sensor under the passenger seat or from the ebcm under the car if so how will i test it should it be unplugged

sorry for question but i am not that good in the electricity

 

[The_Roadie]

sorry for question but i am not that good in the electricity

Sometimes you have to find a local buddy with experience to show you. Or pay a professional. The schematics and a voltmeter should be all they need to troubleshoot the system. Some things are simply beyond the scope of what people on an Internet forum can teach quickly.

 

[IllogicTC]

care to share?

Sorry I never got back on this. Just crossed my mind just now.

The EBCM receives +B. According to the schematics (2006 wiring, page 13) it provides a +5V reference for the yaw sensor, and a +5V reference for the steering wheel position sensor. The steering wheel sensor also has its own power source through fuse HVAC1, but appears to get its reference voltage for readings to the EBCM from the EBCM module. There is no direct link between the steering wheel sensor and the yaw sensor, and it would make no sense to pass a reference through the EBCM just to get over to the yaw sensor. Plus the EBCM already has a lead (Pin 25, Gray wire) feeding a reference signal TO the steering wheel sensor.

That's where I've come up with the EBCM containing the regulator(s). It receives +12 and spits out two different outputs (the one above, and pin 23 dark green) that are both +5V and provides low references for both of those. Generally whichever module is going to need a particular voltage for reference is going to be the one which provides that voltage locally to the sensors, such as the PCM providing the +5V leads for engine-related sensors, though there are times in some vehicles where setups run against this convention.

Notice the flow of wiring in the diagram you provided. The regulator within the steering wheel sensor is connected to two parts with a third one unused. There is also a second sensor setup that also has dual sensors. The steering wheel sensor provides measurements of both the actual position of the wheel (two sensors for correlation check), and steering wheel speed sensors (how fast you're turning the wheel, and two sensors for correlation). The wheel position sensor is the one getting +5v from the EBCM as it's easy to say locked-left is 0 volts and locked-right is 5 volts.

The two attached to the regulator are the speed sensors, which produce an output between 0 and whatever the regulator provides (probably 5, maybe another number) depending on how fast the wheel is being turned. This system is likely designed to anticipate what the driver is doing, such as freaking out and whipping the wheel in a particular direction, in an attempt to better retain control of the vehicle. Turning the wheel slowly would probably induce pitiful voltages at the outputs, like say 0.1 volts, while moderate turning may produce say 2.5 volts. It's kind of like having a small crank-up generator attached to a light bulb, the faster you crank the brighter the bulb gets.

I don't mean to try sounding condescending or like some d-bag professor at an Ivy League school, I'm just trying to elaborate on my understanding of the system so that others may better understand it too, just in case they're curious.

 

[aboturky839]

i got three codes that are C0035 C0040 AND C0292

 

[aboturky839]

i tested the green wire for the EBCM connector that is the 5-volt reference comming out from the front fuse box and found it have 0.200 volts while in the end of the connector testing it from the pin it have no power at all even pin 25 for the steering wheel position sensor it have no power what should i do for get the power back

 

[aboturky839]

Anyone knows if it could be a bad fusebox or it could be something else

 

[IllogicTC]

i tested the green wire for the EBCM connector that is the 5-volt reference comming out from the front fuse box and found it have 0.200 volts while in the end of the connector testing it from the pin it have no power at all even pin 25 for the steering wheel position sensor it have no power what should i do for get the power back

Strange, the diagrams usually show when something channels through one of the fuse boxes to get somewhere else. In this case it doesn't, it shows a dark green wire heading straight from the EBCM to the yaw sensor. Have you tried getting underneath and locating the EBCM, and testing directly from the module?

 

[aboturky839]

Yes i did but it is not working

 

[The_Roadie]

If you're not getting 5V coming out of the GRAY wire on the ECBM, there's your problem. No power to the module, or it's dead. Or your traction control switch is off.

 

[aboturky839]

Actually I did bring a used EBCM that I tested before putting it in my car and I was still having the same problem

 

[aboturky839]

You mentioned that my traction control is of and yes it is because I dont have a 5v power to the yaw rate sensor even the EBCM connector pin 23 doesnot have power but I said that testing the dark green wire comming out from the fuse box is 0.200 volt and it loses power in the EBCM connector to the yaw rate sensor I still didnot test the wheel position sensor because I didnot know how to reach it can you tell me how

 

[budwich]

Yes i did but it is not working

what does this mean??? are you saying that you checked for 5v at pin 23 (D. GN.) on the EBCM?... NOTE: there are couple of D GN wires one also pin 26... this one won't give you any voltage or low so make sure you are checking the right wire / pin. Forget going anywhere else until you confirm this condition at pin 23 D.GN. ...

As roadie says, you either have a bad EBCM or bad powering going to it (which will be your next check.... there are two power conditions going there).

 

[aboturky839]

i mean that when i remove the connector from the EBCM and check the voltage for pin 23 there is nothing 0 voltage i changed the EBCM and i still have the problem

 

[budwich]

sorry but I think you still need to clarify so that I / we understand. You remove the connector from the EBCM unit (I don't even know how many connectors are on it... ONE?) and then you measure pin 21 on the EBCM or the removed connector... hmmm??? Actually, if you remove the only connector on the unit, you aren't going to be able to see any 5v either way as you need to have the EBCM connected to see the 5v. Maybe I misunderstand...

 

[aboturky839]

View attachment 33723
this is the EBCM
View attachment 33724View attachment 33724
This is the connector
pin 23 must have voltage running even when the connector is unplugged anyway i tested it both ways unplugged and plugged i still dont have any voltage



sorry if the picture is not good

 

[budwich]

ok thanks.... indeed it has only one connector so to check for the 5v ref, you need to have unit plugged in (probably key in on) and have to find some way to probe the back of the connector to measure for voltage ... "pin probe" maybe. Anyways, you should further make sure that you are indeed getting the two 12v voltage sources coming into the unit (with key on).

 

[The_Roadie]

Agreed. The ECBM is the SOURCE of the 5V reference voltage, so it has to be plugged in, properly powered up, and have a good ground, for it to work.

 

[aboturky839]

i tested the D-green wire while the connector is plugged in and car idling and i dont have power i bought another new EBCM but i still had my problem

 

[budwich]

as I suggested, you need to check for 12v power going into the unit. The 5v volts doesn't come out of thin air.

 

[aboturky839]

what pin the the 12v power on the connector

 

[The_Roadie]

what pin the the 12v power on the connector

Get the schematics!

 

[aboturky839]

i have them but do you mean the positive voltage terminal because it have power through it

 

[aboturky839]

can anyone help because i cant figure what wrong in the car

 

[aboturky839]

could it be that the yaw rate sensor, EBCM and the wheel speed position sensor need to be replaced

 

[The_Roadie]

Statistically, not likely they all fail at once.

Start by checking the power and ground at the ECBM, as suggested. You said you had "power through it", but what specific wire (color and position) did you check? And even if there's 12V on a pin, doesn't mean the ECBM is "powered up" if the ground is bad. You must confirm the ground wire has zero volts on it - as compared to a known good ground such as an unpainted spot on the frame.