Hey guys, I just PM'd Rev, but it looks pretty late where he is and I need a running car ASAP, so any help is appreciated. Reverant's instructions and my results are below. This is a MS3 basic in a 1993 with a 1.6.

I just got the time to try this today. Now my MS is acting very strangely. with the key set to "on" I only have a battery light on the dash (wideband gauge is off, etc) and the MS is completely unresponsive. When I turn the key to "off" the tach starts buzzing loudly at 1K RPM and the fuel pump turns on full blast. Since the only wiring I changed was the injector harness, I unplugged that in the bay. With the injector harness unplugged, I can connect to the MS only when the key is set to "off" or "acc". When I turn the key to "on" the MS dies.

To confirm:

cyl 1 is wired to 3U
cyl 2 is wired to 3V
I installed a pin in 3Y and 3Z and wired them to cyl 3 & 4 respectively

I installed a jumper on JP11 and and moved the bridge on JP10 from the left and middle pin, to the right and middle pin (closer to the outside edge of the mainboard)

I'm assuming that this is an issue with the jumpers, but I'm not sure how to proceed... Any help is appreciated.

Thanks,

Skye

 

update - I didn't change anything, but now I can't connect to the MS at all in the car. Also tried reversing jumpers and I get the same result... Did something get fried in the ms?

 

Further troubleshooting:
- Pulled and checked every fuse in the car
- Fuse is good on MS mainboard and nothing looks burnt (
- Confirmed that the main relay is working
- Car behaves normally in all key positions with no ECU in car (tach does not jump in off, car will crank, dash lights on when set to "ON")
- With ECU in car, wideband gauge will turn on when key is on "ACC" but turns off when key is set to "ON" or "OFF"

I'm not sure why the MS is getting power on ACC, but losing it when set to on. Also not sure why it seems to be getting power when key is off (fuel pump runs constantly).


Not trying to spam, just documenting my blind panic

 

Stop randomly trying stuff. If the ms is powering on with the key off then something is wrong. Wires crossed, floating ground, relay has gone bad, something. Get a multimeter and start measuring what's going on without your ms plugged in. Make sure your power and ground are sorted out before you do anything else.

 

Wait, don't you have a '94 1.8L?

 

100℅ 93 1.6, which is why you had me add the extra pins to my ecu connector, right? I'm going to test power/ground to the MS when I wake up, but it's 1:40am where I am right now.

 

This all started when I was reinstalling my MS in the passenger footwell. The DB37 had some wires with exposed ends from the PO, and I'm a dumbass and didn't trim them off. I think they shorted when I was plugging everything back in, because I heard some relays click several times when I moved the MS. I've been prodding away with a multi-meter today and have at least confirmed some things are working properly.

This is all with no ECU in car

The good:
-All fuses are good
-Main relay is testing good outside of car and I also confirmed it is getting 12v on contact A&B when key is set to 'ON'
-Car will crank
-Stereo powers on as it should ('ACC' and 'ON')
-Diagnostic 12v is good at ECU plug and engine bay box

The bad:
-ECU pin 1A has power at 'OFF' and 'ACC', it does not have power when is is 'ON'

So before I posted this I ran back out to the car and checked pin 1A while grounding to the chassis instead of the grounds on the ECU connector. Apparently the constant 12v at pin 1A has been working properly (doh) this whole time. I'm actually losing (not completely) grounds at on the ECU connector when I turn the key to 'ON'.

Pin 1A to Chassis - 12V constant (yay)
Pin 1A to 3A/3B/3C/3D - 12v at 'OFF' or 'ACC'. 0.6V at 'ON'


I can build an engine or fab my own parts, but I'm a complete electrical noob. I'm trying to learn, but can anyone share their EE ways as to how I could lose ground in this way? The ECU seems to ground basically straight to the chassis. I checked the ground on the right rear of the block and it's clean.

 

I'll take a look tonight; need to look over the schematics.