SWPS Centering.

[clive f]

my `98 Vette had a duff steering wheel position sensor, new ones not available for this year, bought a very expensive second hand replacement from a US breakers, which I believe is working, , its now fitted onto the car, I had to remove the steering rack to fit a new harmonic balancer so this seemed like the ideal time to replace the sensor as well, the sensor centering pin wasn`t removed until the new sensor was located into the green housing on the column, and the wheel not turned after this, so all put back together fine.
driving the car after the first couple of miles the usual TCS light pops up, and error code TCS1288, SWPS returns, I`ve also had a service message to center steering, and from what I`ve been reading on the usa forums its possible to center the sensor once its been replaced.
I`m fine mechanically but electrics are the work of the devil! plugging in the tech 2 Ive run a steering test, see photo, should analoge and digital both read zero at the same time?have also taken a screen shot of the data on the magnasteer, with the data there, which wasn`t evident on my old sensor, I assume that the replacement sensor is working, but, somehow it needs centering.
so the sensor itself cannot be moved as its fixed into the green housing on the steering column, that leaves the option to either change the tracking to line up with the voltages on the meter, or, somehow change the voltages in the sensor reading?
I`m now at a loss, there are countless threads on various forums talking about replacing the sensor, but nothing I can find detailing how you can actually centre it, I have the 4 big reg GM service manuals and there is no mention of this centering in any of them, so perhaps someone on here in the UK might have some knowledge?
I could take it to Ian Goss, or Top Cats, but I`m on the Isle of Wight so I`d like to be able to crack it myself before I have to spend £100 plus just to get on the car ferry.

 

[Oneball]

Does this help?

Can You Center A "USED" Steering Wheel Position Sensor Using A Tech II? - CorvetteForum - Chevrolet Corvette Forum Discussion

C5 Tech - Can You Center A "USED" Steering Wheel Position Sensor Using A Tech II? - I have a 1999 and they quit making the sensor. I was told a used one could be adjusted with a Tech II (whatever that is) by some parts guy on eBay. It's my only option so I'm trying to find out if the guy was...

www.corvetteforum.com

 

[clive f]

yes thanks, read that one but does`nt go into enough depth to help solve the problem, thanks for looking though.

 

[Oneball]

Based on other cars I’ve worked on the ecu will automatically do a self centring after start up and drive. There’s no actual procedure.

This is what I’d do:

If you use the link and a multimeter that’ll confirm if the sensor is centred on both digital and analog. The tech2 data suggests it is not as they should both be 0

Id also go for a drive and see what the readings are again, have they changed?

 

[clive f]

I connected up the tech 2, with front wheel off the ground, engine running, steering straight should read 2.5v, however the steering wheel position at 2.5v is ever so slightly to the right sort of 1 o clock instead of 12 o clock, this is what strikes me as strange, I`d expect the steering wheel position to be at 12 o clock, as in driving in a straight line, so the computer does its checks in the first couple of miles and determines if all is ok, to my mind its as if I need to rotate the sensor itself so the steering wheel lines up straight if you see what I mean, if I have the steering wheel in the correct straight line position the voltage reads2.44v.

As mine is a 98 car, I`m pretty sure from reading on the American forums that this sensor only has digital not analogue outputs?

readings where the same after driving.

 

[Oneball]

Looking at the tech2 the 2.5v is the analog output.

I don’t think it has to be exactly 2.5v at centre.

Are your tie rods the same length both sides?
have you rotated the steering wheel and seen where the mid point of the rack is?

 

[clive f]

yes it has an analogue output for voltage, the later ones have analogue and digital in angle readings as well, as shown in the second photo, or so I`m led to believe.
I think you are right on the 2.5 v I think there is a very small margin for error there, I remember reading about it but cant remember the exact figures, will double check tie rods when I get another chance to play on sunday, perhaps my new second hand sensor is duff as well? when you read about these problems people just fit another and that`s it job done.
being a 98 car these parts are not available any more, there is another second hand one on ebay at the moment for just under £700, it will be a lot more than that once it landed in the uk no doubt lol. I`t would be nice to just be able to switch it all off, the active handling is gone, tcs is gone, is just warning lights that need to b gone for mot testing. perhaps If I cant sort Ill just pull the dash bulb on the warning light.

 

[oelarse]

Here is a "footprint " of my steeringsensor signal when moving my steeringwheel from left to right .
When my steeringwheel is centered my analog voltage is 2.49 volt as it should be .
The C1288 set when the analog voltage is outside of the 0.2-4.8 Volt range
Since you have the Tech2 I recommend you to initiate a snapshot when the 1288 code appear.
You can configure the Tech2 to start recording values from the EBCM picture in your first post .
After the C1288 appear review the snapshot and check and see if the analog voltage is outside of the 0.2-4.8 volt range

 

[teamzr1]

If this would help to define your problem

1997-98 the ETBCM, ABS, was mounted to the back end of C5
Where in 1999 that controller was moved up front by the steering rack
Not sure if the SWPS were the same for both designs so could be an impedance mismatch if wrong SWPS was installed

There was a TSB where there was an issue that if there was not enough wiring slack for the connector of SWPS
would cause odd reporting of steering angle
Also, if of the 4 wheel speed sensors, and issue with them or their wiring would trick the ETBCM into thinking the front wheel angles
were not pointing the same as one reporting different MPH then the other to angle reported by SWPS

If you have a good OBD-II scanner that would connect to the ETBCM there as I show below several PIDs that would show if there was a mismatch in what is reported

Also, if your scanner tool does bi-directional control could test from ETBCM each solenoid to assure controller is not commanding one front wheel to have a bit of brake pad pressure causing a wheel to drag causing different in yaw angle or SWPS angle

Bi-directional command control tests



Here is most of the control of SWPS and the PIDs for that



There is digital and analog PIDs for some functions

 

[Stingray]

Also, if your scanner tool does bi-directional control could test from ETBCM each solenoid to assure controller is not commanding one front wheel to have a bit of brake pad pressure causing a wheel to drag causing different in yaw angle or SWPS angle

If you take the car for a short drive and then touch the discs you'll soon find out if there's a pad under constant brake pressure!

 

[Chuffer]

This is a very long shot but may help . My Jeep Grand Cherokee has ABS and ESC with yaw sensors . I know its an SUV with serious off road capability and not a Vette but I had issues after fitting new front calipers and abs sensors . The big issue was a total failure of a 3 month old Bosch battery during the three days off the road doing the work. Got a replacement battery and during test drive of new brakes had all sorts of problems with brakes being applied on one wheel or the other due to yaw systems loss of memory . Turning the steering wheel from full lock to opposite lock two or three times whilst stationary re learned the system and cleared the fault codes .

 

[teamzr1]

This is a very long shot but may help . My Jeep Grand Cherokee has ABS and ESC with yaw sensors . I know its an SUV with serious off road capability and not a Vette but I had issues after fitting new front calipers and abs sensors . The big issue was a total failure of a 3 month old Bosch battery during the three days off the road doing the work. Got a replacement battery and during test drive of new brakes had all sorts of problems with brakes being applied on one wheel or the other due to yaw systems loss of memory . Turning the steering wheel from full lock to opposite lock two or three times whilst stationary re learned the system and cleared the fault codes .

Chuffer you have a good point as to battery quality but also as to voltage level within the ETBCM
As seen, a battery could have the correct voltage level but also could have weak cell(s) so not very good at handling current loads
Relays such as one in ETBCM can cause higher current loads on battery

Controllers do not work well under 12.5 V and has been a common issue, esp as to voltage drop
With the 97-98 C5s being the ETBCM is in the ass end that is a long way from the battery up front so there is not only voltage drop but
also, more current load to the parts within the ETBCM . The smaller Gage wire also does not help as to voltage drop.

A common problem is there is one small relay inside and due to voltage/current issues that relay degrades as current load is heating the piss out
of that relay and then odd failures occur

I have replaced this $2 relay on several C5s that were having odd problems
Here is the ETBCM opened and the small relay





Being the ETBCM and SWPS also uses 5 volts then any issue of voltage drop or degraded relay could affect the functions connected to it
Clearly want to make sure reading the 5 and 12 volts at the ETBCM to see if voltages are within the margin of error

If oelarse measured 2.5 volts then that would be center
Is it possible the wheel alignment is at fault so SWPS is reported center but YAW and wheel speed sensors say different ?

Looking at the DTC reported C1288

The Vehicle Stability Enhancement System (VSES) is activated by the Electronic Brake Control Module (EBCM) calculating the desired yaw rate and comparing it to the actual yaw rate input.
The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration.

The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer.
If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle's yaw motion by applying differential braking to the left or right front wheel.
The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side-slip rate error.
The side-slip rate error is a function of the lateral acceleration minus the product of the yaw rate and vehicle speed.
The yaw rate error and side-slip rate error are combined to produce the total delta velocity error.

When the delta velocity error becomes too large and the VSES system activates, the drivers steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.
The VSES activations generally occur during aggressive driving, in the turns or bumpy roads without much use of the accelerator pedal.
When braking during VSES activation, the brake pedal will feel different from the ABS pedal pulsation.
The brake pedal pulsates at a higher frequency during VSES activation.

 

[Chuffer]

Very well presented info TeamZR1 and very informative . The more tech that goes into vehicles , the more potential issues caused by dodgy sensors or voltage / current drop sending out spurious alarms and fault codes . I the case of my Jeep , a supposedly brand new battery just totally died , wouldn`t take a boost charge and put a big spanner in the works !

 

[teamzr1]

Hi Chuffer
I do not know where batteries come from for your country but here in the USA GM gets theirs from China
Time they get here on a slow boat new batteries can be discharged and quality of them are not that good to start with
From then on the battery never fully recovers with weak cells.

We see all kinds of problems in Corvettes because of all the controllers and functions they have

Huge problems seen with the new C8s as there is over 27 controllers and 11 on-board networks and a lot of the problems
are from battery that have one or more weak cells that cannot handle all the current load
With all the downtime the Corvette plant had due to this china virus crap brand new C8s out on their lot could not be
started due to battery already too low

In fact since the 2006 C6 came out GM has to sell as an option a battery tender to keep trickle charge on battery as all the controllers
when car is off, still are active to some point and drain battery
I even keep my 1999 C5 on a battery tender when not being driven

Big screwup with C8s and other GM makes as now any automatic software updates (TSBs) are done Over The Air (OTA) using either Onstar
or cellphone airwaves
Bitch is this can be done when car is parked and that process is long and draws battery down

Worse is there have been OTA software download screw up that when done does not shut down and people 1-2 days later
go to start their C8s and car is totally dead as battery drained and have to call GM to come jump to get started

Really need a battery load cell tester also to check quality of battery once in a while, but I suggest any C5 or newer
to use a battery tender if car sitting more than a few days

As cheap as $20 like this one :

100 Amp, 6/12V Battery Load Tester

Amazing deals on this 100 Amp 6/12V Battery Load Tester at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[Chuffer]

Hi TeamZR1 ,
At least I don`t have all that hassle with my good old fashioned analog age C3 ! Although it is always hooked up to a battery tender when stored in the workshop . It have owned it for 5 years and have no idea how old battery is as it was in the car when it arrived from Japan in 2016 . It has never missed beat so far .
As for the Grand Cherokee battery , it was an expensive heavy duty Bosch product as i wanted the comfort of knowing it would crank over a 5.7 Hemi in all weathers . It still probably came from bloody China though and had sat on shelf for ages at the dealers from long before Covid lockdowns in the UK . I took it back to the dealer who load cell tested it and proved it was bad battery . Got a new replacement with no hassle .
Interesting and very disconcerting to hear about all the problems with the C8 . A real bummer that one .

 

[teamzr1]

A battery tender will expand the life of the vehicles' battery

Both my 1999 Corvette and old tank, a 1993 Cadillac Deville stay on tenders for at least last 14 years and batteries for both are like 15 years old
My 99 C5 does not get driven at all for cold winter 6-7 months
Yet once I go to start it, fires right up

I hardwired both cars so the tender wiring connector is outside the cars, so do not even have to lift the hood

 

[oelarse]

Good and interesting info from teamzr1


The small relay on the picture above belongs to the later C5 versions 01-04 .
This small relay supply power to both the pump and the solonids
On the earlier C597-00 ebcm's has two relays , one for the pump and a second feeding supply voltage to the solonoids
A "normal" draincurrent on C5 should not be above 30mA ( mine is 28mA) and a good battery should last for several weeks without causing any issues .
If I leave my car for more than a month a use my CTEK maintens

 

[Stingray]

I've never needed a battery tender - my cars get driven. I change batteries when they've given decent service life - I don't wait until they die. Batteries inevitably deteriorate over time and I need my cars to start away from home, not just at home.

Unless cars are parked-up for ages it's IMO better to spend your money on batteries than to spend it on tenders. It's not as if Corvette batteries are expensive. I've just done a "precautionary" battery change on my C7 at 6 years old for the princely sum of £82 (delivered) from Tayna batteries. It's only a drop in the bucket of Corvette ownership costs.

 

[teamzr1]

Good and interesting info from teamzr1


The small relay on the picture above belongs to the later C5 versions 01-04 .
This small relay supply power to both the pump and the solonids
On the earlier C597-00 ebcm's has two relays , one for the pump and a second feeding supply voltage to the solonoids
A "normal" draincurrent on C5 should not be above 30mA ( mine is 28mA) and a good battery should last for several weeks without causing any issues .
If I leave my car for more than a month a use my CTEK maintens


View attachment 12846

View attachment 12847

Yes the Corvette ETBCMs broke down as to
1997-2000 MY
2001-2008 MY
This caused part numbers
Part Numbers: can be :09360921,09356971,09356961,0935696 or with some Variation
DTCs that trip related to ETBCM
C1214, C1218,C1221,C1223,C1232,C1233,C1234,C1243,C1261,C1265, C1284, P1571

Also, there is a difference of ETBCM if the Corvette has or does not have active handling (V and M model ETBCMs)
The bad relay I showed above was from my 1999 C5

As to voltage draw, depends on what options the Corvette has, the more controllers, more features stored in temp memory
the more the draw is so much so as mentioned starting with the C6 GM sold the battery tender as an option
More draw if in cold winter or hot summer, they cause more draw.

 

[clive f]

wow, thanks for so many informative replies!! I think I`ll get the wheel alignment sorted first and see where that takes me, I have a sneaky feeling that this might be the culprit.
The car is a 98 with the M coded EBCM, I have managed to source a replacement a couple of years ago from a fellow club member on here, and that is now working fine, no more abs codes which is a great relief, I do wonder at time if I bought the wrong year of manufacture car, just my luck that some components are no longer made or serviceable .
Team ZR-1, thanks so much for the info, did you manage to get your circuit board removed from the ebcm casing? very interested as I know they were potted in with resin during manufacture, if there is a way to remove it without destroying the circuit board it would be very useful if I could get my old unit repaired so I have a valuable spare for future use on my car.

just to add the battering is under 12 months old and on trickle charge when not in use.