T87 Swaps

kidturbo

kidturbo

Piston Tester
Jul 21, 2010
2,534
1,360
113
Somewhere On The Ohio
www.marinemods.us
Also between projects this week, I solved the VR to the 9V current driven square wave sensor issue.

Done, fix, solved, no swapping speed sensors required, AND for a special bonus, I replicated the 5v TOS wire output from the A50 at the same time.. Beautiful circuitry work I must say...

Na, who am I kidding?? I can't take credit where isn't due. But I did hire a slick young man with a fesh masters in electrical engineering, who designs custom musical equipment and builds electric guitars, to fix it all this up for us.. He scope verified my patterns, played with the maxx chip a bit, and provided exactly what I requested. A $500 breadboard with our answer...

First spin outa the box with the T87 running a stock A50 VR sensor tracked to 4k RPM clean, while also replicated the same pulse 5v version of output on a different line. ALL, using power from the 9v Ref going to the new style sensor. Way better than my mess of wires. Reminding me why I never mind paying very smart people..

Here is my New mess. Still not pretty, but good enough to make a couple prints now. About $35 in materials.. So this is sweet if it checks out, and I don't drop it.. lol





154e102828b051609039fbdc78fe3a91.jpg
0a98fe6255ea73f07a2e54c33dd79320.jpg
caacaf10709d09ae01f217d5bf053a3a.jpg
eaad0c2d313fa113bfc4552682e213f9.jpg
b423f0b5684ea1d90855c865447625e9.jpg


Sent from my SM-S901U using Tapatalk
 
Last edited:
  • Like
Reactions: 1TRIKHD, gmc502, pl_silverado and 2 others
pl_silverado

pl_silverado

Active member
Jan 29, 2012
140
106
43
Good stuff! Can’t wait to get the prototype and put a couple thousand miles on it. I’ll find all the kinks in no time with what I put my truck thru 🤣
 
  • Like
Reactions: kidturbo
kidturbo

kidturbo

Piston Tester
Jul 21, 2010
2,534
1,360
113
Somewhere On The Ohio
www.marinemods.us
pl_silverado said:
Good stuff! Can’t wait to get the prototype and put a couple thousand miles on it. I’ll find all the kinks in no time with what I put my truck thru 🤣
Click to expand...
I seriously need to dig thru my desk for your TCM again. Its getting deep.. Been testing with the one I pried outa the case, so you'll start with a fresh CVN, and best shot at it killing it.

Tonight the plan is to see if this new TOS pulse reads correctly on an LMM. Then can start wiring up the rest of the T87 harness, to this valve body pile on my bench.
 
  • Like
Reactions: pl_silverado
kidturbo

kidturbo

Piston Tester
Jul 21, 2010
2,534
1,360
113
Somewhere On The Ohio
www.marinemods.us
Ran a full barrage of tests against this little VR circuit upgrade breadboard last night. Overall, it seems pretty dang solid for a mess of jumpers and chips connected together by perforated aluminum foil.

The conditioned circuit [Probe 1] actually produces a cleaner square wave than the new style bolt in OEM speed sensors [Probe 2]. I used twisted pairs, clocked the sensor, swapped sensors, traded probes, and even switch TCM inputs lines, yet no difference. But the T87 doesn't seem to mind the noise. However, it's All or Nothing with these new style current driven sensors. There is no Bad Signal.. And if you increase the air gap to the wheel by more than about 0.050" all pulse signal is lost. Picky Picky they are..

Anyways that doesn't effect us now. And this VR conditioner Maxx chip doesn't seem to mind an air gap of 0.200" plus, so moving on. The only related issue left to reslove, is a pair of DTC's set due to the VR board key on voltage supplied to the TCM.

P077C Output Speed Sensor Circuit Low Voltage Permanent EPA-Perm
P07BF Input Speed Sensor Circuit Low Voltage Current EPA-Curr, MIL

Few pages back I noted that the Low side on our pulses with these new GM sensors never seems to drop below a 1.25v. And that I noted some Min/Max values in the bin. So rather than 0-5v square wave, those operate in more of a 1.25-6.5v range. Yet the TCM will reconize and track a 0-5v pulse from an Arduino, or this new applified conditioner setup just fine. But, it's unhappy with seeing anything Below 1.25v at key on..

So need to raise the floor, and fiddle with to get the proper peak to peak, which should clear those DTC's, and this part be done.

Old-New-VSS.jpg
 
Last edited:
  • Like
Reactions: pl_silverado and juddski88
kidturbo

kidturbo

Piston Tester
Jul 21, 2010
2,534
1,360
113
Somewhere On The Ohio
www.marinemods.us
Couple more hours testing and have successfully mechanically cleared the ISS and OSS low voltage codes.. While issue is resolved, the OSS code remains a Permanent for now. I'll either flash or electrocute it back to normal in future testing, but either way, it will stay clear.. Board runs quite well actually, all naked and clamped in a vice.. We have came to an understanding...

20240620_144813.jpg

The key to these new speed sensor DTC' triggers, which I verified in a bin, is a Key-On voltage test. It says signal voltage pass is 0.335v to 4.663v and fail is 0.250v or 4.750v. If you disconnect the sensor, ya got zero volts, if you short to Ref line, ya have 9 volts. Both outside the range, each will set a different code.

So while the TCM is happy with our new emulated 9v pattern, which runs about 6v peak to peak when everything is connected, it still wasn't happy with the 0.0v floor on our line at key on. By using a pots, I injected a 2.5v value and raised the floor on our new pulse. That made the TCM 100% happy with the emulated signal now from Key-0n to 100mph and back to Key-Off. Then I raised and lowed the line floor to values found in the bin file, and the DTC triggers match up perfectly.. Feeling confident it won't wake up stupid one morning, and set an anoying P077C, unless there is an actual issue.

E35B-T87-ISS-Cleared.jpg

Here is our current peak to peak comparison with OEM sensor in Green and VR Emulated in Yellow. Both floors are raised now, but the peak voltage needs lowered on the emulator to get a perfect match.

OEMvsEmulated.jpg

Now that I know everything it requires, can map our peak to peak values close enough. Then it's time to print some prototypes with adjustable voltage pots, so we can fine tune these puppies..
 

Attachments

  • OEMvsEmulated.jpg
    OEMvsEmulated.jpg
    97.6 KB · Views: 4
Last edited:
  • Like
Reactions: pl_silverado and PureHybrid
Jakezed22

Jakezed22

Active member
Dec 2, 2016
255
125
43
Last night i was looking at the diagram for the T87 and noticed that little "9V" on the vss line, i thought oh man i hope they havent changed sensor type on these..... i wonder if a tr6060 output shaft reluctor would trigger the new sensor? im guessing not which why youve done what youve done here (if its same as an allison).
 
kidturbo

kidturbo

Piston Tester
Jul 21, 2010
2,534
1,360
113
Somewhere On The Ohio
www.marinemods.us
Jakezed22 said:
Last night i was looking at the diagram for the T87 and noticed that little "9V" on the vss line, i thought oh man i hope they havent changed sensor type on these..... i wonder if a tr6060 output shaft reluctor would trigger the new sensor? im guessing not which why youve done what youve done here (if its same as an allison).
Click to expand...
I was wondering the same about your manual trans..

The older Screw In speed sensors are sine wave VR, while the T87 and up use a bolt in 9v ref square wave. Thus the breadboard with mosfets and 20 jumpers ya have above..

Take me 10 days to get some printed up for beta testing. Or go to a T42/3 using sane setup you have now, and canbus should be ok. 50/50...



Sent from my SM-S901U using Tapatalk
 
  • Like
Reactions: Jakezed22
Jakezed22

Jakezed22

Active member
Dec 2, 2016
255
125
43
kidturbo said:
I was wondering the same about your manual trans..

The older Screw In speed sensors are sine wave VR, while the T87 and up use a bolt in 9v ref square wave. Thus the breadboard with mosfets and 20 jumpers ya have above..

Take me 10 days to get some printed up for beta testing. Or go to a T42/3 using sane setup you have now, and canbus should be ok. 50/50...



Sent from my SM-S901U using Tapatalk
Click to expand...
I’ve been looking at sensors all day online, an Allison input sensor looks darn close to a tr6060 output. And the 15/16 Allison’s use the 9v sensor. I gotta find one to measure diameter and length.
 
kidturbo

kidturbo

Piston Tester
Jul 21, 2010
2,534
1,360
113
Somewhere On The Ohio
www.marinemods.us
Jakezed22 said:
I’ve been looking at sensors all day online, an Allison input sensor looks darn close to a tr6060 output. And the 15/16 Allison’s use the 9v sensor. I gotta find one to measure diameter and length.
Click to expand...
Allison be a good place to start.

Part# listed a dozen pages back. We even considered making a printed adapter, but not likely an option. So next option is finding an off the shelf sensor to start with that can be adapted. But these are a current based 2 wire, more common in modern ABS.

I have a couple Allison on the bench if ya want measurements.

Sent from my SM-S901U using Tapatalk
 
  • Like
Reactions: Jakezed22
Jakezed22

Jakezed22

Active member
Dec 2, 2016
255
125
43
kidturbo said:
Allison be a good place to start.

Part# listed a dozen pages back. We even considered making a printed adapter, but not likely an option. So next option is finding an off the shelf sensor to start with that can be adapted. But these are a current based 2 wire, more common in modern ABS.

I have a couple Allison on the bench if ya want measurements.

Sent from my SM-S901U using Tapatalk
Click to expand...
Sure that’s he great. Here’s the stock 6060 sensor.
IMG_6370.jpeg

IMG_6371.jpeg
 
Jakezed22

Jakezed22

Active member
Dec 2, 2016
255
125
43
kidturbo said:
Same as the ones I have.

That's the new style, so it should work fine with the T87.

Sent from my SM-S901U using Tapatalk
Click to expand...
I’ll wire it up and give it a spin. This would
Be from a stock 2010 Camaro, I thought they are VR sensor.
 
You must log in or register to reply here.
Top Bottom