spark on fidle but led17 won't fire msd

themaintenanceshoppe · Sat May 06, 2006 6:38 am

msnse024s13 ms1v3.
spark runs perfect on fidle circuit. Connected vb921 to led17, switch cobase output spark from fidle to led 17 connected msd6al to correct pin on db37. I don't get any spark or tach from msd box. Do I need to turn spark invert off. Where is the correct diagram for connect vb921 to led17. on msnse site it says jumper to x11 where is it's not on my board.

Post by **jsmcortina** » Sat May 06, 2006 7:11 am

As you have an MSD you do not need the VB921. Connect the wire from LED17/D14 to a spare DB37 pin.
X11 is now called IAC1A and connects to pin 25 on the DB37.

Just run a wire straight from the (-) leg of D14 over to IAC1A and connect pin25 to the white MSD wire.

If you are running stepper idle you will need to use a different pin, say pin 36 in which case the wire would be connected inside to IGN and the VB921 not connected to anything.

James

PS. do not cross post

themaintenanceshoppe · Mon May 08, 2006 5:13 am

I tried it. No spark no tach from msd. Tried inverted spark on and off. led blinks but no spark. I've been trying for a month. Itried bypassing the vb921. I Tried it with the vb 921 and resistor. I just can't get spark This is driving me nuts!!! What am I missing?

Post by **jsmcortina** » Mon May 08, 2006 5:17 am

Could you post exactly what you've wired where on the board to drive your MSD, which DB37 pin and what jumper output etc.

This worked with FIDLE you say? You ought to be really close to getting it to work with LED14 then.

James

themaintenanceshoppe · Mon May 08, 2006 5:24 am

soldered a wire from negative or flat side of d14 to ign out. connected point negative inout trigger of msd to s5 of relay board.
Give me 5 minutes and I will tell you how i did it with the vb921.

Post by **jsmcortina** » Mon May 08, 2006 5:26 am

Where does S5 on the relay board connect? I don't think it connects to pin36/ignition out.

James

themaintenanceshoppe · Mon May 08, 2006 5:30 am

For the use of the vb921. Iconnected a 330 ohm resistor to the top of r26 and then to igbtin. Iremoved r57 and installed a jumper to replace r43 Ithen installed the jumper for th vb921 to igbt out. spark is inverted. I set megatune to led 17 or d14 spark output a. CAN I PUT A TEST LIGHT ON S5 OUTPUT AND CRANK IT OVER TO SEE IF I GET A BLINKING SIGNAL OR WILL SOMTEHING FRY?

themaintenanceshoppe · Mon May 08, 2006 5:34 am

From all of the schematics I've seen Pin 36 does connect to s5 or pin 11 of relay board. I am going to go test right now with my fluke.

Post by **jsmcortina** » Mon May 08, 2006 5:37 am

I'm pretty sure that S5 does NOT connect to pin36 so it is the wrong pin. It should be safe to connect a _small_ test lamp from +12v to S5 and see what happens.

Follow the wire from pin36 on the Megasquirt connector through the relay board wiring loom and see where it is going.

I have a feeling (unconfirmed) that S5 on the relay board connects to what is now IAC1A on the V3 board. You can safely use a resistance meter to check continuity between these. If it works then the jumper wire on your Megasquirt board should be run from D14 (-) over to IAC1A.

James

themaintenanceshoppe · Mon May 08, 2006 5:41 am

If you go to the relay board site in the schemtaics it shows pin 36 to s5 or position 11 of relay board. I just took my fluke to it from igbt out to s5 is infinite resistance...... HMMMMMMM where does igbt out come out at the relay board?????? I looked for the signal on the relay board out puts and couldn't find it.

themaintenanceshoppe · Mon May 08, 2006 5:52 am

Well yu are right I just checked the relay board site and it has changed since i built my unit and they now list s5 as output to coil for ms2 only. THANK YOU FOR ALL OF YOUR HELP!!!!!! i WAS LOSING MY HAIR.

P.S. I JUST CHECKED S5 WITH AN OHM METER FROM THE RELAY BOARD TO THE IAC CONTACTS ON THE MS1 iT doesn't eve connect to any of them.

Post by **jsmcortina** » Mon May 08, 2006 1:45 pm

themaintenanceshoppe wrote:If you go to the relay board site in the schemtaics it shows pin 36 to s5 or position 11 of relay board. I just took my fluke to it from igbt out to s5 is infinite resistance...... HMMMMMMM where does igbt out come out at the relay board?????? I looked for the signal on the relay board out puts and couldn't find it.

IGBTOUT only connects to the IGBT(Q16) the pin you should be testing is IGN. That goes to pin36 (follow the traces on the board) but where it goes outside depends on how the relay board cable is wired. Ask your vendor.

James