Direct ground at polly fuse f1

[Blatzy]

I have a ms II v3.0 that up untill a couple of days ago was working. We had done some work on the car and when i went to fire the car is the injectors were constantly firing and the there was no response with the computer. I took the ecu out of the car put it on the stim and niticed that the f1 was getting hot. I the removed the f1 and noticed that there is a direct short on the out side of f1. When we were working on the car we were doing some welding but we did have the ground disconnected. Does anyone have any clues of where I could be getting this short.
Thanks
Blatzy

[Blatzy]

I have been doing some more trouble shooting and I think the problem is in the st232 switch. Does this sound to be a possibility for the cause of a short?

Thanks
Blatzy

[Blatzy]

Apparently welding on a car that the computer installed is not a good idea. With the help of Matt Cramer(DIYAutoTune) problem appears to be resolved. Blown r19. Once again thanks Matt.


Blatzy

[Blatzy]

OK I thought the problem was fixed but I am only partially there. I am still grounded out somewhere. Here is what I have.
1. the MS II v3 was working perfectlly untill I did some welding on the car.
2. I did have a blown r19 replaced it and now half of it works, most inputs(clt,tps,iat)
3. on the stim and in the car I have no rpm signal. At first I thought that I shorted the stim so I replaced the 555 chip in the q1, same result.
4. have tried rebuning the embedded code.
5. I noticed that if I move the rpm swith on the stim back and forth I do get a faint rpm signal.
6. I did make the test led and when I checked pin 24 I got a faint but solid led.I then removed the 555 chip to isolate the the input signal and I still have the same faint but solid led.So my guess is the signal is coming from the MS II, but where?

Does anyone have any suggestions?

Thanks
Blatzy

[Matt Cramer]

What RPM input circuit are you using?

[Blatzy]

Matt,
I have the MS II set up for the hall circuit (GM HEI) and the rpm circuit on the stim is switched to PNP, but that is the switch that when I move it back and forth the pump light comes on and the I1and I2 will start to flash verry dimly.

thanks
Blatzy

[Matt Cramer]

I'd use a LED tester and see if it blinks at TachSelect. If it does, follow it through to TSEL and see if you're losing the signal somewhere.

[Blatzy]

Matt,
I tried using the test led to chek for the tach signal at tachselect but I got a solid led I then removed the jumper then checked with a multi meter I get 12v at tackselect 0 at optoin. I the removed jumper optoout and tsel and I get solid led (4.9v) at optoout and nothing on the tsel.

thanks
Blatzy

[Matt Cramer]

If you apply 12 volts to OptoIn, you should have 0 volts at OptoOut.
If you apply no voltage to OptoIn, you should have 5 volts at OptoOut.

[Blatzy]

Would it be safe to assume that the problem would be with the stim, since I have no way of contrilling the voltage(solid 12v no matter what I do with the stim) the problem would be with the stim. But I do have the same problem when the ecu is in the car.I did just replace the hei module so I guess I should check the coil. Once again Matt thanks for the help and insight.



Blatzy

[Matt Cramer]

You do have a way of controlling the voltage. Remove the TachSelect-OptoIn jumper and you can jumper OptoIn to either nothing or a 12 volt source. It is definitely not safe to assume anything about the Stim.

[Blatzy]

Does the voltage at the tachselect represent rpm signal? Be cause once the jumper is removed I have a solid 12v and connot adjust test led to flash. Does this sound right. I am doubtful about the stim but I am trying to isolate where the rpm signal comes in and how to isolate the stim from the ms II to check only the stim. I guess the question is whether I can power the stim without the ecu and produce an rpm signal?

Blatzy

[Matt Cramer]

With the standard Hall effect circuit jumpers (no pull up resistor installed) you should not have 12 volts at OptoIn. If you do, something is damaged in the circuit.

[Blatzy]

What I am trying to figure out is does the tachselect represent the input for the tach signal and if so the 12v should be coming from the stim.


blatzy

[Matt Cramer]

TachSelect is connected directly to pin 24 and is the input from the Stim. However, if you have it jumpered to OptoIn and added mods to the opto circuit, it may not accurately reflect what the Stim is doing.

[Blatzy]

I removed the jumper from the tachselect to the optoin and I am still getting the 12v at the tachselect(this is why i am thinking the stim is bad). When I installed the new 555 chip and the new Q1 I powered it up with a bridged solder joint at the q1. Could this have damaged the new 555? I do have a new stim and MS II on the way but this problem is causing me to loose sleep.

Thanks
Blatzy

[Blatzy]

Problem resolved,bad coil and stim (what are the chances of both of them being bad) Ecu is installed in car and running. I can't than you enough Matt for all of the help and insight.


Thanks
Harold