Tracing a bad shorted wire or water short from Sensor Connector to ECBM?

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
2006, 6cyl, 9 7x @ 66k miles.
Driven in NYS winters, but annually "Rust Check" pro applied annually.
It isn't too rusty :smile:, hood is mint .
I try to do as much searching as possible (I do all my own wrenching) but not seen something like this.
Hoping more tech savy might colabotrate thanks for all you folks do!!!!

Last summer 2014 new (Napa Premium SKF) front hubs w/sensors.
In all cases below -ABS Activation at crawl to stop.
No Dash lights, no codes thrown/stored.

In Jan 2015 RF Wheel sensor no reading - scanned bad, R&R just Sensor in 6 month old/new hub warranty and it fixed it.
Now same, issue so again I got warranty part R&R entire RF Wheel hub & sensor.
But to my surprise still have ABS activation at crawl to stop.
(Spray & cleaned checked that frame to sensor electrical connector).

Made a 15 foot extenstion with 2 extra OEM junkyard ABS Sensor connectors.
Easy to plug & play by just turning wheel and reaching in behind it to connectors.
I moved wheel sensor (via long extention cord electronically) from RF HUB Sensor wheel to LF Frame EBCM input.
(I had - em and I don't have a great VOM I trust to try and solo hold wires and wheel spin test it).
It works and is giving reading.

When I swap and put LF HUB Sensor wheel to RF Frame EBCM input.
It failed to read.... so both wheel sensors are working.

Guess from what I read here to start I might ...
Pull Ground at EBCM and clean for the heck of it.
Pull & clean check all electrical conectors on EBCM for corrosion, electronic cleaner, reinsert and might be fixed?

1) So the EBCM is under Drivers floor board in the slop right?
Can it be unplugged as it sits in place or do you have to pull it off frame?

2) With my extension whip - can anyone tell me which 2 connector pin #'s I might check at the ECBM for continuity?
Or the colors of the 2 lines in (what connector) I might be looking for?

And open to any other suggestions ....

Oh at standstill start up, brake data feed scanner ...
LF, LR and RR all read 2 MPH
The RF trouble one reads 0 MPH

Start rolling out, straight... the LF, LR and RR all read true same MPH as accelearation.
The RF trouble one reads jumps like to 200mph in a split second and then locks at 3.99 MPH
Have no idea if there is a faulty message (3.99?) there like direct short low resistance or ground?
Probably not a "Open" because when you unplug the RF sensor only and leave it off & start car...
You get the ABS and StableTrac lights and live data read like 34mph and its froze.
So I am guessingt it fails a initial start resistance scan then?
Plug it in (even though it wont work proper as noted) and all is back to same action as start of this paragraph.
 

AtlWrk

Member
Dec 6, 2011
674
Good work so far. You can download Service Manuals here, including colored wiring diagrams :thumbsup:

http://gmtnation.com/forums/topic/361-need-service-manuals-get-them-here/


Short answer for the RF wheel sensor:
Tan and Dark Green wires, Pins 27 and 26 (respectively) in the middle row on the EBCM connector. IIRC the EBCM connector can be removed with everything else in place.

Good luck and let us know what you find!

EDIT: Be careful probing the terminals, as they are quite small and easy to distort with a DMM probe or the like.
 

coolasice

Member
Oct 27, 2013
1,019
Northern Maine
here is the schematic of the ebcm sensors, you need to check continuity of the wires to the sensor from the ebcm. more then likely you have a damaged wire somewhere between the two that is shorting together.
 

Attachments

  • brake schematic.png
    brake schematic.png
    1.6 MB · Views: 35

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
PERFECT, thanks for the quick replies, that's exactly the info I was hoping to find.
Probably be over the weekend before I get to it again, but will update.
Oh and I did download the manual too for future use.

It's probably too much wishful thinking its just some wet sandy salty crud shorting at the EBCM.... time will tell.

All the best - Regards
 

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
Slow progress here.... Too damm cold!
Today Up on ramps, jacked a little further , creepered under it and the connector sure was grungy and wet-ish. Numerous clean spray downs and then pulled that back cover off connector, again wet-Ish all sprayed elec cleaner air dried, back together.... Air blow out.

Road test No joy. Same brake wheel speed read outs as above noted.

I'll need to get to the family lift next to pull from wheel and trace wire continuity to pins noted in diagram with my new handy long jumper.

If that checks good, can I pull the electric brake control module and drive it with it off? But I can let it set to (like the PCM was done while it set ).

...if it's the ebcm ...can I send it somewhere potential fix and re install w/o GM coding it again? Know where they are rebuilt I read some mixed opinions?
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Reading everything you've done so far, before I would dive into the EBCM, I'd be looking at the hubs again. I've had this same problem with the ABS kicking in at low speed with brand new, albeit cheap, hubs. Once I replaced them, it was all good.

It might not be the sensor or circuit but the reluctor wheel inside the hub, especially if it was doing it from installed when new. I know that SKF are supposed to be a quality brand but they are sold under the NAPA name so they might be their second rate value line. How do you know they're made by SKF? If going by what the counter guy says, I would trust him as much as politicians. They don't really know where they think they really come from.

What I would do is pick up a pair of used hubs cheap at a U-Pull yard and start by replacing one, test and then the other. Then, and only then, if the symptoms are still exactly the same, I would look at the EBCM.
 

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
Thank you very much for the info.

I thought it was hub and yes even a new one might be defective.
Familiar with NAPA stuff as it is family business...They have a value line Proformer (MFG?) 1 year warranty and the higher level and cost 3 year (SKF) bearing which I used.

I was long winded above...not to argue.... I could get another new one off the shelf anytime...

I made a long extension cord. With used GM proper sensor wire connection ends. Tested each sensor side by cross feed 1 at a time & drive.

With extension I ran the new RH hub sensor wires then all the way over to the LH input connector on frame at wheel opening and it read as the LH hub on road test fine.
Matches the Rear wheel speeds fine - So appears RH hub sensor is outputting fine

When I fed the LH sensor extenstion all the way over to the RH input connector on the frame,... nothing....same readings

Thus why I am thinking from frame connection to EBCM or internal issue not ahub.


Next step using that long extension, jumper with continuity tester see if I get reading in the 26 & 27 pins.
Might find which (if one is open or grounded). It was too darned cold and I will get it up on a lift next.
(I did this connector clean up on ramps.

I was kinda hoping the at rest 3.99 mph reading while the others are at 2 - that someone might chime -might be a code for a short - open etc....?
When the sensor is unplugged totally at wheel and you start-drive -it throws an instant ABS & Traction dash light stuck on right at start up I recall.
Plug all back in and at least dash light goes away, so must have some sort of quick start up -system check.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
No argument taken at all. The more info the better I say. Just got confused (which doesn't take much for me!) about the extension use results.

Could very well be either bad wiring, ground or EBCM. I know I have seen more body rust in my 06 Saab with 158k Km than I have in my 02 TB with 278k Km, including the hood (the Saab's is Swiss cheese). There must have been more recycled Ford content those years. I would believe that the ground could be compromised due to corrosion.

I wonder if just swapping an EBCM from a wreck yard would work or be recommended? Probably anything from a low mileage TB or Envoy would work.
 

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
Continuing my pursuits.... got the SAAB up on the lift this morning.
Off with the main connector at EBCM and the Left Front at frame to sensor connector.
Plugged in my long whip extension made with used connectors off junkyard....

No issue with full continuity from each wire solo, no cross short and no short to ground on either wire.
Off with the EBCM to see if it was soaked? Found Pins 16, 13, 26, 41 &44 all common grounds.
All wheel sensor pins check thru the front connector pin (thru to wave solder joint) on back PCB side.
And no other pattern found, part looked OK so no joy.
Doesnt appear all that servicble and not seeing Moldule shops offering to fix these types.

Electrical Contact Cleaner as much as I could, air blew that out and sun dired.
Back together,,,no change at road test, brake data readings all the same and it's all acting same.

Sure appears the 2006, 9 7x - GM # 15813053 or interchange # 545-51539 is sort of a odd- one off issue?
Anyhow off the the Ebay there appears to be a few used exact matches.

Anyone just plug & play on a EBCM from like SUV's without Tech II programming ?
(don't take my word on this). I was told its a speed wheel sensor thing, like AWD (no selection) vs. 4WD (manual or slectable).
Or traction control - stabiltrack programmming vs. not. So not necissarily a VIN code looking for matching hardware item.
Thoughts?
 

Attachments

  • EBCM in place.JPG
    EBCM in place.JPG
    128.1 KB · Views: 10
  • Jumper test1.jpg
    Jumper test1.jpg
    140.1 KB · Views: 10
  • 2006 9 7X EBCM 1.jpg
    2006 9 7X EBCM 1.jpg
    145.2 KB · Views: 13

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
FWIW .... In case others have issues..... Ugh. On ramp & creeper ( easy enough since I already cleaned and antiseezed those pesky lil torx screws on the lift ) ....

So EBCM -Swapped with an exact matching p/n equal as label on mine off a wrecked 2006 SAAB 9 7x and exact same issue. $90.

I have ordered 18/2 cased wire, and some shrink wrap, I might just solder in and run new wire all the way from sensor to EBCM for that RF (2) wire line now. My DMM is a cheapie and while I had no direct line short together, nor short to ground, as well both showed continuity.. I didn't check resistance levels against a spec (? Ohms Amount unknown-anyone? .) or LF vs RF

So next weekend or so back to family lift, will double & recheck lines thru connectors for resistance and ohms LF vs. RF but if nothing glowing I'll have the new line all made (have extra connectors) cut the current 2 wired free and join my new line at EBCM.
 

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
Gosh darn it.... all new wires from wheel sensor to the # 26 & 27 pins at EBCM large connector.
Check of RF Hub is putting out the 100+ MV AC doing the rotation test w/DMM, thru the connector into the full new wire lengths ....
All back together ............Still no joy.
What the heck else can it be?
.... same 3.99mph at standstill on RF the other (3) 2.00mph.
This sux....
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Just playing around with the Tech2, I also saw that all my wheels register 3mph (or kph) while parked so this must be normal. You would need to find a way to capture wheel speed data while braking to see what is happening. Apart from a Tech2, maybe an ELM327 with Car Gauge Pro can do it. I'd have to play with mine to see if it's possible. Other than that, and I hate saying this but, maybe a dealer can diagnose it.

How about this, what about a rear wheel sensor in the axle? Maybe the rear is registering faster and thus, making the EBCM think that a front wheel is locking up. Again, you would need data capture capability to confirm this. Just throwing ideas out there.
 

coolasice

Member
Oct 27, 2013
1,019
Northern Maine
NYFlapjack2 said:
FWIW .... In case others have issues..... Ugh. On ramp & creeper ( easy enough since I already cleaned and antiseezed those pesky lil torx screws on the lift ) ....

So EBCM -Swapped with an exact matching p/n equal as label on mine off a wrecked 2006 SAAB 9 7x and exact same issue. $90.

I have ordered 18/2 cased wire, and some shrink wrap, I might just solder in and run new wire all the way from sensor to EBCM for that RF (2) wire line now. My DMM is a cheapie and while I had no direct line short together, nor short to ground, as well both showed continuity.. I didn't check resistance levels against a spec (? Ohms Amount unknown-anyone? .) or LF vs RF
700-10000 ohms from pin to pin at ebcm connector (sensor plugged in), with dmm set to ac volts you should get 100+mv when the wheel is spun by hand... have you checked what code you get when abs light is set?

ADDITIONAL:
Test for 850-1350 ohms of resistance between terminal A and terminal B of the wheel speed sensor.
⇒ If not within the specified range, replace the wheel speed sensor.
Test for greater than 100 mV AC voltage between terminal A and terminal B of the wheel speed sensor, when spinning the wheel.
 
  • Like
Reactions: Mooseman

coolasice

Member
Oct 27, 2013
1,019
Northern Maine
AND JUST BECAUSE:


Ignition OFF, disconnect the harness connector at the EBCM.
Ignition ON, test for 0 volts between the low reference circuit terminals of the appropriate sensor listed below and ground.
• LF Sensor circuit terminal 13
• RF Sensor circuit terminal 27
⇒ If not the specified value, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the wheel speed sensor.
Test for 0 volts between the signal circuit terminals of the appropriate sensor listed below and ground.
• LF Sensor circuit terminal 12
• RF Sensor circuit terminal 26
⇒ If not the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the wheel speed sensor.
Ignition OFF, test for infinite resistance between the low reference terminals of the appropriate sensor listed below and ground.
• LF Sensor circuit terminal 13
• RF Sensor circuit terminal 27
⇒ If not the specified value, test the low reference circuit for a short to ground. If the circuit tests normal, test or replace the wheel speed sensor.
Test for infinite resistance between the following signal circuit terminals of the appropriate sensor listed below and ground.
• LF Sensor circuit terminal 12
• RF Sensor circuit terminal 26
⇒ If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, test or replace the wheel speed sensor.
Ignition OFF, disconnect the harness connector at the appropriate wheel speed sensor.
Test for less than 2 ohms between the appropriate signal circuit terminals listed below.
• LF Sensor circuit terminals 12 at the EBCM harness connector, and terminal A at the WSS harness connector
• RF Sensor circuit terminals 26 at the EBCM harness connector, and terminal A at the WSS harness connector
⇒ If greater than the specified value, test the signal circuit for an open or high resistance. If the circuit tests normal, test or replace the wheel speed sensor.
Test for less than 2 ohms between the appropriate low reference circuit terminals listed below.
• LF Sensor circuit terminals 13 at the EBCM harness connector, and terminal B at the WSS harness connector
• RF Sensor circuit terminals 27 at the EBCM harness connector, and terminal B at the WSS harness connector
⇒ If greater than the specified value, test the low reference circuit for an open or high resistance. If the circuit tests normal, test or replace the wheel speed sensor.
If all circuits test normal, replace the EBCM.

Component Testing

Ignition OFF, disconnect the harness connector at the suspect wheel speed sensor.
Test for 850-1350 ohms of resistance between terminal A and terminal B of the wheel speed sensor.
⇒ If not within the specified range, replace the wheel speed sensor.
Test for greater than 100 mV AC voltage between terminal A and terminal B of the wheel speed sensor, when spinning the wheel.
⇒ If not within the specified range, replace the wheel speed sensoR
 
  • Like
Reactions: Mooseman

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
Thanks all!! Helps bouncing these things off and keeping my focus... It really hasn't been a troublesome SUV!

Mooseman I know it is weird why my Launch CRP 129 brake scan shows live data as "0" on RF and 2.00mph on the other sensors (3) at stop, while engine / key is on.
The instant you pull forward RF jumps to "3.99" and the other (3) all read exactly as the speedo does in prefect unison. From then on until slow braking to complete stop the live data shows RF at 3.99, other (3) in unison to speedo, while at final low slow braking stop -ABS dumps-buzz.

Coolasice, unfortunately I do not get any set codes, stablitrack and ABS lights do not come on unless I unplug the master fuse. Then they reset all by themselves at fuse plug in engine restart. Can't get it to throw a code (at least not a light for my CRP129, unsure if brother's Genesys OTC or if only a GM Tech II would read deeper OEM specific codes?).

Coolasice thank for the other DMM probe tests -wow yes this is great next steps,exactly what I can do now. I did have the 100+mv ac on the spin test on the RF hub thru sensor all the way thru end of my new added (2) encased insulated wire whip for line # 26 and # 27 (which is soldered and heat shrinked into the main EBCM harness/connector now, old #26 and #27 cut free now. This list you gave me is great especially the cross between 12 to 26 and the 13 to 27 as I am interested it them more so now (read below) Thank you for the next steps, that will be a great guide for fault isolation thanks!

I can tell you pin # 16 (large) and 13, 26, 41 & 44 all show to each as common grounds in DMM continuity tests (pre your info above). Per my bench probing the actual EBCM standing pin half -off the SUV (my post #9). So this is on the EBCM not my wiring harness. What the EBCM plug is expecting there to those pin #'s. This is very confusing to me and perhaps the wiring drawing (in Post # 3) has line # 26 and # 27 mixed?, or the input at wheel sensor really doesn't care for which is ref low or sensor as it's AC MV? I can tell you on mine pin # 26 is ground - should it be low ref in drawing? ...in probing the actual ECBM. Yet labeled in wiring drawing (post 3) as the sensor and #27 the opposite. I checked it like 4 times....but I may as well report that. Wiring wise my pin # 27 is Tan 3rd in from RH side, to the B - circuit 833 from the easily seen molded in # 29 on the EBCM plug. And as well my pin # 26 DK Green 4th in from same and is to the A side 872 circuit. As I said I have triple checked these back & forth as it doesn't appear to jive with wiring diagram... at least to me.

Anyhow renewed and encouraged thanks for all the aid...... I will advise...regards.
 

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
Thank you all.... I believe I have figured it our and all I can say is I am hot, tired and that it is quite unreal what I discovered.

I will need to drive it somemore, write a logical summary for posterity and I will have to take photos to show you/support my findings of the issue.

It is a phew :thumbsup: and a :mad: :hissyfit:
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
You sir will be a subject matter expert on this system. I was also tapped out.
 

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
One issue not to be lost, which I did not really see this answered......I am no expert and can not say if this is true for others.

But I did an exact P/N, make/year/AWD and Hollander exchange EBCM electronic half exchange without programming of any type, GM Tech II or otherwise.
Attached photos shows (Top one) P/N tag off the EBCM on my original and the lower tag off the $89 delivered used EBCM I bought and played with. It was plug & go no issue, easy swap no brake fluid or hydraulic lines opened.

Now that my SAAB 9 7x it is fixed, and I drove it a bunch road testing.... I can vouch that on my 2006 SAAB 9 7X...
I successfully exchanged the original EBCM (electronic half only) to a used ECBM (electronic half) - back & forth.
I am back to the original on the 9 7x.

When running either EBCM's without any reprogramming nothing was required or DTC's being thrown.
Operation on either appeared same in gravel skids with activations, slow and fast stops, all acting very normal.
 

Attachments

  • 2006 9 7X EBCM PN compare.jpg
    2006 9 7X EBCM PN compare.jpg
    83.1 KB · Views: 5

NYFlapjack2

Original poster
Member
Jan 22, 2012
27
[SIZE=small]Summary...on my 2006 SAAB 9 7x L6 cylinder. [/SIZE]
Issue was - ABS activation at almost all stops and no DTC codes or dash lights.
Repair - required Left Front Wheel Sensor attention / replacement (did full hub).
Hard lesson learned... I didn't trust my tiny $20 DMM for continuity and open testing - while at the same time I had to much faith in my Scanner for ABS fault identification and fixated on a false reading for wheel speed sensor. The Launch CRP 129 is a good unit, I used it on numerous including AUDI and I do like it, just appears this is another case of the orphaned sort of a GM but is it - SUV?

Unfortunately this repair was delayed due to Launch CRP129 ABS scan, on the SAAB 9 7x -its diagnosis software tool when the 2006 SAAB 9 7x was selected.
Then the live datastream appeared not to be providing true data.
Right Front will read zero while parked or in motion, before and after repairs.
Meanwhile Left Front datastream display appears to be in accurate and reading parallel speeds to the rears.

Interesting to note that the CRP129 does provide accurate wheel speed data when plugged in the same 2006 9 7x but telling the CRP129 software to scan as a GM Envoy.
After hours of failed repair research and trials all towards RF sensor, EBCM and wiring… the discovery was made in “Envoy” scan mode Right Front was fine the Left Front wasn’t reading.
Just the opposite indications while scanning in 2006 SAAB 9 7x mode. [SIZE=small](I later discovered scans telling the CRP 129 it was a 2007, or 2008 9 7x it showed all 4 speed and sensors equal and parallel, change it back to the 2006 and RF goes to 0mph no reading).[/SIZE]

Photos attached of the (2) datastream records of a perfect working ABS - StabilTrack 2006 SAAB 9 7x.

Anyhow R&R - Left Front hub w/sensor, (2) RF WSS wires butt soldered shrink tube back to original 2 wires from RF WSS connector to EBCM. EBCM trialed with both the used EBCM after repairs and now back to my original EBCM (both worked fina = same) - all is fixed.
 

Attachments

  • Slide1.JPG
    Slide1.JPG
    106.3 KB · Views: 5
  • Slide2.JPG
    Slide2.JPG
    72.3 KB · Views: 6
  • Slide3.JPG
    Slide3.JPG
    94.4 KB · Views: 5
  • Slide4.JPG
    Slide4.JPG
    80.1 KB · Views: 5
  • Slide5.JPG
    Slide5.JPG
    88.1 KB · Views: 4

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
The joys of owning a bastard child Saab. Probably a software glitch in the programming of the scanner. I'd use Envoy for everything on that scanner just to be sure.

Now go crack open a cold one :Lager Louts:
 

Forum Statistics

Threads
23,273
Posts
637,499
Members
18,472
Latest member
MissCrutcher

Members Online