3.4 Conversion to DIS runs with problems (Page 1/3)
DMax OCT 22, 08:00 AM
Hello

recently I throw out my DIZZY, and installed a DIS.

Used the wiring diagram from the fiero forum here.

Put in a Bin with A1 mask
Car starts, en runs good, but after about 2 seconds, the SES light goes on. Seems to be code 42.
I also have no tach.

I also detected the advance makes no difference with the bypass connected or disconnected.
The Wire is not iterrupted from the ICM to the ECM (measured it)
changed ICM and ECM, without result.

Someone who can help me with this?
f85gtron OCT 22, 09:04 AM
Double check the wiring at the dis module and at ecm. It's possible the dis icm is faulty. That's what generates the tach signal. It should respond to interrupting the bypass signal.
Ron
lou_dias OCT 22, 10:34 AM
I've had to replace my ICM every 4 years...
phonedawgz OCT 22, 12:01 PM
Make sure the white wire that runs from the ECM to the DIS is in the correct place and has continuity.
DMax OCT 22, 01:53 PM
The bypass wire is connected to the A on the ICM, the wire ICM-ECM to the B, the TACH to the C

I do get a rpm signal in tunerpro, so I guess that the white wire to the ECM works fine.....

I tried with 2 different ICM modules, and 2 different ECM => I believe it would be too much coincidence if they where both faulty.

Not to mention the engine runs ok, but just like you would disconnect the EST bypass

Does anyone knows how if something else can trigger the code 42, and does an activated code 42 can cause the advance works like the bypass disconnected?

just guessing........

DMax OCT 22, 02:07 PM
oh, and one more question....
Never pay attention to it before, but if you diconnect the est bypass, would the tach stop then?

Try to pinpoint the cause of this.....

grtz, D
phonedawgz OCT 22, 04:29 PM
The tach should work with the ECM bypass connected or disconnected.

Both the code 42 and the fact that the timing doesn't change are related.

1227730 correct?

$a1 or is it $88?

Stock pick up on the 3.4?

90 Firebird tach?
DMax OCT 22, 04:34 PM
A1, stock pickup on the 3.4, 1990 tach
phonedawgz OCT 22, 04:47 PM
Ok - lets try this - with the tach wire disconnected do you still get the code 42?

Here a link that explains the GM bypass system - https://www.youtube.com/watch?v=mxPdxGqRWvc&t=120s

[This message has been edited by phonedawgz (edited 10-22-2017).]

theogre OCT 22, 05:01 PM
One "Ground" from ECM to DIS isn't a power ground... Iffy "ground" here and/or Ignition Ref line can cause DTC 42.
See my Cave, Ground "Myth" notes

DIS tach line Does Not use a "Tack Filter" as HEI does. jump/remove the filter.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave