MS3 / MS3 VR "no Signal" issues - no rpm help...

[dcg9381]

I've got a MS3 / MS3x unit from DIYAutotune. 3.57 board. Good stuff. I'm also using their wiring harness to keep things simple.
I'm wiring a Toyota motor - a Tacoma 2RZ, which has factory cam and crank VR sensors. I understand the setup, but I've never done VR before.
My current issue is that I've got nothing in the composite logger while cranking. No pulses indicated that I can tweak. I've looked at both "tooth" and "cam" signals in the logger - and looked at the log file. No signals indicated.

My guess is that I'm doing something wrong that's pretty basic.

I have basic sensor logging. I'm not connected to coils and not trying to fuel injectors. Just making sure my inputs are right.

I've verified the following:
1) Basic ignition settings for VR (36-2 missing tooth) - Cam sensor on MS3x:
http://www.2rzturbo.net/wp-content/uplo ... s_temp.jpg

2) I verified the unit was setup for VR per the manual (http://www.msextra.com/doc/pdf/html/MS3 ... e-1.3.html):

• P1 jumped 1-2
  J1 jumped 3-4
  I adjusted the pots at R52 and R56 7 turns to the left.

3) Wiring on the MS3 connector:

• VR sensor is wired to pin 24 (positive)
  VR negative is wired to pin 1

You can see my wiring diagram here: http://www.2rzturbo.net/wp-content/uplo ... G_MS3X.jpg


4) Did a tone trace from my VR sensor connector to the MS3 connector. No problem. Verified continuity.

5) With a DVM:

• I get what appears to be pulsed voltage at the VR sensor connector while cranking.
  I get what appears to be pulsed voltage at the MS3 connector, pin 24 when cranking.

My scope is down, so I just ordered a pocket version... I'll eventually scope JP1 pin 2 (input of the VR sensor past the wiring harness)


6) Tried several variations on the composite logger, making sure I was cranking for 10 seconds AND logging to a file. The logs contain no data beyond version and typical stuff. Cam isn't logging either..

The only thing that I'm doing that might be a little odd, the shields of the VR cam sensor, VR crank sensor, and the MS3 wiring harness (provides a shield) are all tied together.
Even if I wired this thing backwards, I should see a signal on the logger? Again, I suspect I'm doing something pretty basic wrong.. Anyone got ideas?

[DaveEFI]

A scope makes things easy - but check for an AC signal with a DVM at VR out. If none, but there is at VR in, chances are R56 needs adjusting. Turn it clockwise a turn at a time, and check for a signal.

[dcg9381]

Dave, thanks for the reply... By VR out, I assume you mean:

Crank:
"... the output at pin 14 of the processor socket" (MS3, v 3.57) - (ref: http://www.diyautotune.com/tech_article ... _index.htm)
Isn't the daughtercard piled on to the U1 socket here?
Or are we referring to VR in as JP1 And VR out as j1 (3-4 jumper)?

Cam:
The 'Cam' signal can be picked up on PIn 18 of JP2 on the MS3 card, on Pin 18 of the MS3X card, Pin 1 of U7, or Pin 3 of R32.

[DaveEFI]

Not that familiar with the V3.57 board, but IIRC VRout on the main board is pin3 at J1

[dcg9381]

So I got a simple scope up and working, but this is a mystery to me.
I've got a beautiful wave form between tach in (VR+) - pin 24 and sensor ground (VR-) pin to the DB37 That's at the MS3 unit unconnected.
Here's the wave:



Now when I scope JP1 Pin2 (jumpered or unjumpered) I get nothing... Literally nothing. That's at least part of why she's not indicating RPM. So a break between the MS DB37 and that pin, right?
Wrong. I've got continuity on the unit between pin 24 and JP1 Pin 2 - My waveform goes dead somewhere in there...
And if I trace if back to the VR sensor itself, continuity all the way back to the sensor (positive) side.

I pulled in a stim, simulated VR, with a 5V pull up on the stim, I get a nice wave on JP1 Pin2 after messing with it for a while.

I haven't traced sensor ground all the way back.. On the MS3 v3.57 board, where is the best place to check for that Pin1 ground?

Could this be a pot issue or should I work on tracing that Pin 1 ground?

[DaveEFI]

Have you tried adjusting R56? With it in the default fully anti-clock position it's not unusual to have no signal at all at VR out - depending on the type of input signal. It's also common to have to adjust it between a Stim and the actual sensor signal.

[dcg9381]

Have you tried adjusting R56? With it in the default fully anti-clock position it's not unusual to have no signal at all at VR out - depending on the type of input signal. It's also common to have to adjust it between a Stim and the actual sensor signal.

Interesting you ask:
1) On the stim with the 12V pull up, no adjustment required.
2) On the stim with a 5v pull up, I had to adjust R56 a few turns right
3) I haven't tried adjusting it on the vehicle. I left it in the position that had it working under 5v pull up with the stim. Actual signal on the vehicle is more like 2.2 Vpp.

So the position of R56 can completely kill the signal at VRin? I understand that not having it adjusted can mean no VRout.

[DaveEFI]

As you've probably seen, the signal from the Stim is a square wave. A VR sensor closer to a sine wave. Depending on the type of VR sensor, the output voltage from that can be as low as a volt or so at low revs. The VR input stage conditions the input signal to a square wave. And yes - it's possible to have no signal at all at the output with some pot settings.

The ideal method is to look at the VR output with a scope on the car with the sensor in use and set to the most regular square wave you can achieve - check at low and high RPM.

[dcg9381]

The V1.5 "simulates" a VR wave form. It's got two options these days. It's not really VR, but it's not square either...

So I understand that the two pots condition that VRin wave form via trigger voltage and hysteresis, but my understanding was that the result of that conditioning was produced on VRout. The clarification that I'm seeking is that that pot on R56 can affect the signal shown on VRin (JP1 pin 2)?

I'll definitely mess with R56 more. It's interesting that I had nothing on the stim until I started to turn that pot clockwise, which runs counter to manual instructions. The clarification above is important to me as it determines if I chase a wiring problem (lack of signal could be due to a bad ground on pin1) or if I chase pot adjustment.

[DaveEFI]

The instructions referring to pot setting and the Stim probably don't equally apply to a JimStim where you can alter the pull up voltage.

I'd look with your scope at VR in and VR out with your VR sensor. The idea is to get a stable waveform at VR out which only alters in frequency.

[dcg9381]

Dave, I totally get that. I understand the instructions around adjusting the pots when you can see both sides of the signal VRin and VRout. My issue is, literally, that I have no VRin. I've got a nice wave form on the DB37, but when I plug in to MS, it goes to nothing as measured at VRin.

I'd expect the pots not to have any effect on VRin. I'd expect them to have an effect on VRout. Largely, that's my question - can the value of the pot R56 impact what I see at VRin? The manual says that pot is a trim for the voltage trigger.. I wouldn't expect it to actually attenuate VRin, but I've never done VR before...

[billr]

" I've got a nice wave form on the DB37"

That's the connector on the Stim? Load that output with a 10K resistor, see if the Stim will drive that load OK. Similarly, you could measure input resistance of the MS, I would expect it to be well above 10K.

[dcg9381]

No. That's in the car cranking at the DB37.. It's the wave form in the photo above. Thats what I get when probing pin 24 (tach in) and pin 1 (ground) while cranking.
I get a flat line when I check VRin at the MS3 board...

The stim (configured for VR) does fine in 5V pull-up mode with a little pot adjustment. MS gets that signal and I'm able to adjust it.

[DaveEFI]

Dave, I totally get that. I understand the instructions around adjusting the pots when you can see both sides of the signal VRin and VRout. My issue is, literally, that I have no VRin. I've got a nice wave form on the DB37, but when I plug in to MS, it goes to nothing as measured at VRin.

I'd expect the pots not to have any effect on VRin. I'd expect them to have an effect on VRout. Largely, that's my question - can the value of the pot R56 impact what I see at VRin? The manual says that pot is a trim for the voltage trigger.. I wouldn't expect it to actually attenuate VRin, but I've never done VR before...

Right - understand you now. I don't know the actual sensor fitted to your car - have you checked if there is any resistance reading between either of the sensor pins and engine ground, when not plugged in to MS? What input voltage range are you using on your scope when checking it plugged into MS?

On the V3 board, the component values of the VR input circuit were changed fairly early on. The V3.57 schematic shows it still using the earlier version. I'm not sure if this makes a difference, as I've never used the earlier version.

[billr]

Do I understand correctly now, you have a VR signal to the pad of DB37 pin24, but no signal at the pad of JP1 pin 1 (VRin)? How about a signal on JP1 pin 2, that should be a direct connection to DB37-24? Checked with an ohmmeter? Has the jumper connection (JP-1 to JP1-2) been checked with an ohmmeter? Those jumpers are pretty simple devices, but stranger things have happened!

[dcg9381]

Do I understand correctly now, you have a VR signal to the pad of DB37 pin24, but no signal at the pad of JP1 pin 1 (VRin)? How about a signal on JP1 pin 2, that should be a direct connection to DB37-24? Checked with an ohmmeter? Has the jumper connection (JP-1 to JP1-2) been checked with an ohmmeter? Those jumpers are pretty simple devices, but stranger things have happened!

I have the following:
1) VR signal to the pad of DB37 pin24, but no signal at pin 1 or pin 2 of JP1 when they're jumpered and MS is powered up..
2) I have continuity (0 ohms) between DB37 pin 24 and JP1-2. Which is why it's really strange that I can't get that VR signal.
3) I can get a signal at JP1-2 if I use the stim, but that signal originates from a stronger source (5Vpp)

I haven't checked continuity between JP1-1 and JP1-2, but I have probed both sides of the pins.

[billr]

Take the jumper off of JP1 and see if the signal makes it from pad 24 to JP1-2 with no load on that circuit. At least we are all wondering the same now: how can it not get from pad 24 to JP1-2??? Have you examined things with a bright light and magnifier?

[dcg9381]

First, thanks for the assistance and input...

"My guess is that I'm doing something wrong that's pretty basic."

Yep... And that's what I get for not building the board. Apparently I'm not picking up the correct ground spot when probing the board. I Assumed that one of the screws would work just fine (continuity with pin 1) - but there is some amount of resistance, which is probably attenuating the VR signal.

Where *should* I probe the board to pickup the ground from pin 1?

I have a solid signal on JP1 pin 2 when I ground to pin 1 of the DB37. Saying it another way, get the ground from the connector and I've got signal on the board.


Here's how I picked up signal:
http://www.2rzturbo.net/wp-content/uplo ... s_fine.jpg


Here's how I was probing the board (doing it wrong):
http://www.2rzturbo.net/wp-content/uplo ... ground.jpg

[billr]

So.. do you have signal further along that circuit, like clear out at J1-4, now that you are using a real ground for the probe?

[dcg9381]

It wasn't the ground... Or at least, I seem to be able to ground it as shown above to a screw on the board.
Basically, I bridged the DB37 to MS3 connector and attached one wire at a time until the signal died. As it turns out, when I connect the shield wire - that kills the crank signal. I don't understand it yet. Clip the shield wire and I've got a beautiful VR signal.


Doing this fixes it:



WHY that fixes it, I'm not sure... The shield wire was there as installed in the DIYAutotune harness and I don't actually have it terminated.