Odd MLPS Behavior

[Raymond_B]

Both my MS3/3x and Microsquirt V3 are installed in my truck (1995 F-150 with E4OD). I have everything wired up and the engine (MS3) side is good sensor-wise, but the trans controller side is giving me fits. I have another question about the OD cancel and OD light in another thread, but the issue I have here is with my analog MLPS. It's very odd, with only the Megasquirt plugged in and when I measure voltage across the signal return (sensor ground) and the MLPS analog signal I get close to VREF(4.28v). When I plug the Microsquirt in the MLPS output drops to ~.28v.

So I imagine I have some bad wiring somewhere. I should also mention that I do not have the engine installed, but everything is currently grounded to the battery and frame which are in-turn connected by a lug off the neg. battery cable.

Maybe these questions will help narrow down my wiring mistake.

Can the Megasquirt and Microsquirt share the same sensor ground? All of my gauges and sensors plugged in to the Megasquirt work correctly, TPS, MAT, IAT, Batt volts, etc, etc.

How do you calibrate the trans temp sensor? I have the option for air and water temp, does the code just use that? IAT and ECT are measuring ambient perfectly, trans temp is like -7 deg f.

Also the Megasquirt and Microsquirt are sharing the same power ground, is that an issue?

I feel like this is a bad ground affecting the Microsquirt or the trans harness, but for the life of me I cannot find it.

MS3/3x is running 1.41 beta 4
Microsquirt is running 1.01

Trans Tune

MS3_CurrentTune.msq

Engine Tune, ignore ignition it is not set up.

MS3 3X.msq

Also here is the pinout of my MLPS.

[Raymond_B]

Got the engine in the truck and grounds connected properly, still no joy.

[Raymond_B]

I hooked the Microsquirt up to the JimStim on my bench. I used the "Spare" output to send 0-5v to SPR4 on the Microsquirt. It basically behaved as expected and as I varied the voltage the Tuner Studio gauge reacted showing each gear as I was close to the voltage specified in "Gear Settings". However as I set the voltage to 4.40 (Park) TS showed a "Sel Fault". Kind of weird, but anyway I guess I am able to rule out any hardware issues with the Microsquirt since it tests out OK on the bench.

[Raymond_B]

So either I have everyone stumped or nobody browses this sub forum. I wonder if the issue is because the Megasquirt is supplying the 5v VREF, but the Microsquirt is receiving the signal?? But they are both sharing ground and sensor ground.

I am thinking about disconnecting the trans harness completely and adding in the Microsquirts 5v VREF and see what happens.

[jsmcortina]

Do the other gears respond as expected?

I thought I'd added a "gauge" to show the voltage that the trans controller is seeing, but that doesn't appear to have made it into a released version.

Take a look at the appropriate "adc" channel and convert to volts using the following formula on a calculator to see what voltage the Microsquirt thinks you are applying.

Volts = 5 * ADC / 1023

James

[Raymond_B]

Thanks James, I'll do it!

[Raymond_B]

OK, hopefully the below photo makes sense. The selector gauge does not actually line up with the voltages I input for "Gear Position". I guess I did not look close enough last time, it does show1st, 2nd, and 4th(D), but at different voltages than entered in the tune. If a cell is green (in either table) then the Selector gauge agreed with the gear for that voltage and matched Gear Position settings in the tune. I also logged the RAW AD counts, what they convert to, and the voltage as read by my DVOM. I also noticed that only the PRN1 indicator goes green, but none of the other Gear indicators do in TS.

[Raymond_B]

Do the other gears respond as expected?

I thought I'd added a "gauge" to show the voltage that the trans controller is seeing, but that doesn't appear to have made it into a released version.

Take a look at the appropriate "adc" channel and convert to volts using the following formula on a calculator to see what voltage the Microsquirt thinks you are applying.

Volts = 5 * ADC / 1023

James

The above was done on the bench if it matters.

[jsmcortina]

Enter the 'converted voltage' into the settings.

Jamed

[Raymond_B]

Enter the 'converted voltage' into the settings.

Jamed

OK, will do.