MSefi.com read only forum (Jan.15,2018)

I'm having an issue with getting my spare ports to control my fan. Basically, I'm always getting 12V across S1-S2 (DB37 pin25, 27), and S3-S4 (DB37 pin 29, 31) on the relay board. I have the Power-on value set to 0 and the trigger value set to 1. The first variable is Coolant > 195 hysterisys 5 - no second variable (when I get it working, I will set RPM > 400 to keep the fan from turning on when cranking.) I have tried both PT6 and PT7, and tried all different combinations with my DMM on S1, S2, S3, S4, and I always get 12V between S1 and S2, and between S3 and S4 (and I get 12V from S2 and ground, and S4 and ground - it may be S1 and S3, but either way, I'm getting voltage all the time the key is on.)

I have the MS-II board wired with S12C to JS9, and the 4 wires for the IAC (1A)JS0 to IAC1A etc.

Any changes I made to the spare port settings, I would turn the key off and back on to force a reset on the MS-II, just in case it needed a reboot after setting changes. I just kept getting 12V on S1-S4

For a little background, I had this working before with my original MS-II board - something on the board failed (Seems to be the BIP373 - I've was back and forth with Matt Cramer trying to sort it out, and we've concluded that it's likely the BIP373's, so I've got a replacement and spares on the way), so I have my son's board in its place temporarily. I have carefully examined and compared both boards and both are wired exactly the same. I have checked for cold solder joints (re-touched all joints with the soldering iron to be sure). Everything else seems to work the same as my original board. I'm using the same relay cable, relay board and wiring as I was originally.

Anybody have any thoughts on things I should test to help figure out what's going on.

Hopefully, You are not trying to run the fans directly with MS. You will need to set up MS to operate external relays. the power required to operate electric fans is too much for the board to handle.

No, I'm running it to a 40A automotive relay, since the fan draws almost 20A, and the spare port outputs on the MS, I think, are only rated for .5A.

Any other things that I can check/verify? It would seem logical that it's the wiring on the MS-II board, since my previous board worked (with this same relay board and fan, in the same vehicle). I've checked all fuses, and checked the board (compared to my 'old' board) in great detail, and didn't find any differences or obviously failed components/cold solder joints etc.

Is IAC2 enabled or disabled?

Matt, do you mean in the spare ports configuration settings in Megatune? If so, I've tested voltage with IAC2 enabled and disabled. And, I tried enabling/disabling IAC1 as well - I tried to test all different configurations I could - I tried with the power-on setting to 1 and to 0 for both ports etc.

On another, but somewhat related topic, I got the replacement BIP373 (and 2 spares) in the mail a few days ago. I soldered in one of the replacements to my MS-II board, and put it in my truck and it started up. So, that confirms that it was something with the BIP373. Now (hopefully I'll have time this weekend) I'll try the spare port settings stuff on my board (now that it's back up and running) and see if I get the same problem. If not, then I know that there's something funky with my son't MS-II as far as the spare ports are concerned.

Yes, that's the spare ports. When used as spare outputs, if you have more than one spare output enabled, the IAC outputs don't completely turn off so much as reversing their polarity when they're off.

Matt, thanks, I didn't know that. I had tried testing the voltage with just one spare port enabled, then just the other one, then both, and was getting 12V in all situations. Again, hopefully this weekend I'l test with my board (the spare port problem was with my son's MS-II) now the BIP373 has been replaced and it's working again.

I seem to have it sorted out. I only had IAC7 enabled, but it appeared to be just reversing the polarity for the 0 and 1 trigger (like Matt explained would happen if both were enabled). And, realizing that it was necessary to reboot the MS-II (by turning the ignition key off and back on) after any change, in order for it to take effect.