GM DIS questions

flyguyeddy · Post by **flyguyeddy** » Sat May 06, 2006 4:14 pm

Ok, i have a 96 cavalier with dis. the car originally had a OBDII ignition module that the megasquirt cannot control. I removed it and wired the older style into it and now i have a non-functioning tach and no idle control. the ECU is not seeing any engine rotation.

I piggy-backed the VR sensor and wired in the OBDII module into the fenderwell with no coils hooked up to it and the ref pulse low and hi not attatched as well. (the ref pulse low and hi for the older module are wired into the ECU, so it should be seeing rotation).

should i make a resistor pack to simulate coils?

should i remove the ref pulse signals from the older module and replace them with the OBDII module? will that mess up my ignition advance signal to the current module?

hopefully you gm dis people can help me out with this

wopontour, any suggestions?

Brandon

codebase and megatune version shouldnt have any effect on any of this, however i am running the latest megatune, MSII version 2.3 (i think) and the V3 board.

bluetrepidation · Post by **bluetrepidation** » Sun May 07, 2006 6:43 am

I swapped my ICM with an OBI and it works fine. I'd make sure your VR sensor's polarity is correct to the ICM. Make sure the grounds are good. One should go directly to the ECU. Besides that I'm not sure what your trying to ask?

A.J.

flyguyeddy · Post by **flyguyeddy** » Sun May 07, 2006 9:23 am

bluetrepidation wrote:I'd make sure your VR sensor's polarity is correct to the ICM.
A.J.

it is. the wire colors are the same on the two years of connectors i have.

bluetrepidation wrote:. Make sure the grounds are good.
A.J.

they are.

bluetrepidation wrote: One should go directly to the ECU.
A.J.

it does. stock wiring used on the engine, just stole certain wires from the ecu.

bluetrepidation wrote: Besides that I'm not sure what your trying to ask?

A.J.

I'm trying to get the tach to work and get the ECU to control the idle speed motor. it is not seeing revolutions. do i have to have teh injector circuit hooked to something? right now i just have the injector leads cut and wired to the MS.

flyguyeddy · Post by **flyguyeddy** » Sun May 07, 2006 9:25 am

sorry, i guess i should state that it DOES run. i just dont have a tach or idle control.

tebriel · Post by **tebriel** » Mon May 08, 2006 3:23 am

so it runs, but the signal to your indash tach isn't working? But it's working in megatune?

flyguyeddy · Post by **flyguyeddy** » Mon May 08, 2006 3:56 pm

the signal to the in dash tach is not working. this is not a standard tachometer either, its a serial bus gauge cluster. there is no "tach feed" to the dash. its all in the ECU.

yes, the rpm's work in megatune. its not a matter of the megasquirt not getting a tach signal, its a matter of telling the factory computer that the engine is rotating. when that happens the tach will work and the idle motor will work.

let me repeat: the factory ecu is NOT seeing engine rotation for some reason or another. will my previous ideas work? anyone know?

tebriel · Post by **tebriel** » Mon May 08, 2006 6:13 pm

so the tach signal normally goes to the ECu and then the ecu drives all the gauges correct? You just woudl need to find out what that signal was and recreate it

flyguyeddy · Post by **flyguyeddy** » Tue May 09, 2006 4:37 am

yea, i know. which is why i made this post. if you read my original post thats what im trying to do, i have several options listed, i want to know which one should work. desoldering/resoldering this kinda stuff sucks....

flyguyeddy · Post by **flyguyeddy** » Tue May 09, 2006 8:50 pm

for the love of god...

i really dont wanna return this to stock, i would have to do alot of soldering that is a pain in the behind. can ANYONE help me with this?

PLEASE?!

WOPONTOUR, WHERE ARE YOU?

anyone have a way to get ahold of him like AIM or something?

tebriel · Post by **tebriel** » Wed May 10, 2006 6:20 am

i haven't seen him around.
i wonder if you could wire in both ignition control modules at the same time, and then just use the output from the original to drive your ECU and gauges?
-teb

flyguyeddy · Post by **flyguyeddy** » Wed May 10, 2006 2:07 pm

this is what i tried. ALTHOUGH i have not wired in the reference pulse high and low yet. currently the older MS controlled module is sending the reference pulses. i think im going to try and patch the ref pulse wires into the factory ecu and just run the MS controlled one to the ms and then to ground. that way it follows along with the schematics for the DIS/HEI setup.

flyguyeddy · Post by **flyguyeddy** » Thu May 11, 2006 3:42 am

i have been informed i may need to install a FET signal booster into the reference pulse line cause im sharing it with the MS. is this true? it seems like a plausible concept.

jsmcortina · Post by **jsmcortina** » Thu May 11, 2006 4:08 am

Any reason not to let Megasquirt control your idle ? And try wiring direct into the tacho ?

If those are the only two functions you need from the old ECU that is.

James

flyguyeddy · Post by **flyguyeddy** » Sun May 14, 2006 6:55 am

well, i figured it out. heres what i did.

i used the factory ignition module in the wheelwell. i removed the signal for reference pulse from the mocule thats controlling the ignition to the ECU and ran it JUST to the megasquirt and grounded the low line. (just like it shows for GMDIS setup pages) i then ran all the wires from the factory mocule to the ecu and pigybacked the VR sensor wires so that it would have a sensor signal from the crank. works like a charm.

tebriel · Post by **tebriel** » Sun May 14, 2006 6:02 pm

rockin! I figured something like that would work