Analog in's not working now

[jeffmarsh750]

Just had the unit apart and installed the new dual vr board and now my spare analog inputs stopped working. Have 5 volts and ground at my sensors, 2 pressure sensors. Jump 5 volts into signal and no change on my dash or datalogs. What did I screw up now ?

[Matt Cramer]

Check the voltage all through the circuit to the MS3 daughter board and see if you've lost the voltage.

[jeffmarsh750]

The board has power. The analog spare channels used for fuel pressure and NOS pressure 0-5 are on pins 21 and 22 set as spare ADC13 and EGO2 in. It does not read correctly in the data or on the real time dash. I have a linear 0-5 volt scale. On the dash it just bounces around 39 and 45 (both gauges) Does the same on a data log. Values do not change if I ground the circuit at the pin or if I add 5v. nothing changes. Is this board dead now ?

[jsmcortina]

Do the other analogue inputs (MAP, MAT, CLT, TPS) work ok? If they are ok, then the processor is likely ok.

If they are all causing a problem, then it might be worth doing a voltage check on the board, see
http://www.msextra.com/doc/pdf/html/MS3 ... 4-217.html
The analogue inputs need one pair of those 0V and 5V and if they are not working (somehow) then the inputs wouldn't read correctly.

The analogue inputs are very simple circuits, so if just those three from the MS3X aren't working I'd be more suspect of damage to the ribbon cable?

You can check for the 0-5V input on those signals too. With power off, carefully prise up the ribbon plug a little - enough so you can get a voltmeter probe onto a pin. The pins to check are AN11,12,13. See : http://www.msextra.com/doc/pdf/html/MS3 ... 4-194.html

Be especially carefully not to short out any pins - there's 12V going to the MS3X card and a short from 12V to 5V will damage LOTS of parts of the ECU.

James

[jeffmarsh750]

OK, So I checked voltage at my sensors and have ground and 5 volts. I jumped the 5 volt wire to the pin 22 and 21 at the sensor. 5I am getting 4.99 volts at the ribbon cable in the box as you said to check by lifting slightly and checking at the board. If I plug the sensors in I have .5 volts. I also set the scale on both gauges as 0v =1 and 5v = 5. The both sit at 35 on one gauge and 55 on the other gauge. The exact same readings as if the sensors are unplugged. Bad board ?

[jsmcortina]

The MSQ looks ok.

Remote diagnostics are always difficult, but at this stage you seem to have confirmed that you can get a 0-5V signal at the ribbon cable but the MS3 still responds as if it is getting ~0V. If that's the case then perhaps the MS3 card is damaged somehow.

Perhaps send to Peter Florance for analysis or repair.

James