I have my 4.9 in and wired up. I have wired the ALDL like below, question is how do I run the diagnostics...as the fiero or the Cadillac the engine and transmission came from? It is not wired like the original ALDL from the Cadi.

http://members.shaw.ca/efog/Pen/4.9/4.9%20aldl.jpg

The Caddy ECM that you are installing in your Fiero will operate like the Caddy ECM it is.

The Caddy's BCM (Body Control Module) was able to display the trouble codes on the heater control's display without shorting A-B. Because of that GM didn't build in the A-B shorting diagnostic routine into the ECM. So you lose that simple diagnostic ability. Sorry.

You can however use a Red Devil River 12 pin ALDL USB cable, TunerPro RT and a Windows laptop to read any codes and also scan all the ECM inputs and outputs.

You can also do it using the Red Devil River 12 pin ALDL USB cable, ALDLdroid, and an Android device to read the codes and also scan all the ECM inputs and outputs. Note your Android device has to support host mode.

You can also do it using the Red Devil River 12 pin ALDL Bluetooth adapter, ALDLdroid and any Bluetooth Android device to read the codes and also scan all the ECM inputs and outputs.

Red Devil River ALDL USB cable - http://reddevilriver.com/aldl.html = Comes with free version of TunerPro RT on the disk - Shameless self promotion - This is me
Red Devil River ALDL Bluetooth adapter - http://www.reddevilriver.com/ALDL_Bluetooth.php - also comes with the free version of TunerPro RT - again a shameless self promotion
ALDLdroid - https://play.google.com/sto...om.sgiroux.aldldroid

Also - The Caddy ECM's ALDL connector puts the data on pin M. GM did this with all the newer (1990 ish +) OBD1 ECMs. Pin M is a bidirectional data wire. If you have the simple one transistor ALDL cable that was wired for the Fiero PIN E ALDL connector, it won't work for this ECM. You also can't just move the pin to match up to make it work since the one transistor cable is only capable of unidirectional data flow and not the bidirectional data flow needed by the Caddy ECM.

-----
Make sure you run a switched +12v wire to the Power Steering Switch input on the 4.9 ECM.

[This message has been edited by phonedawgz (edited 05-21-2014).]

Thanks Phonedawgz I will look into it tonight. Just trying to determine if I have a missfire or if it is shudder from the transmission... I am hoping for a missfire. I do get the service engine soon lamp on from time to time so there must be something going on.

Unlike most OBD2 engines, the 4.9's computer can't detect cylinder misfires. To do that you need a higher def crank pick up. The 4.9 only has pick ups in the distributor.

The computer however can tell you why it is displaying the check engine light.

I pulled 4 plugs tonight to check for color...the easy ones of course. Plugs 2 and 8 eight looked real clean, plugs 4 and 6 were both very
black with 4 looking a little wet. Put timing light on all 4 wires and it looks like they are firing on all four. Ohmed 4 and 6 wires back to ecm and they are wired correctly. Ran the engine for a minute or two, shut it off and reached around to the base of each plug with my finger...2 and 8 were hot to the touch and 4 and 6 were only slightly warm. This doesnt seem normal to me, anyone have a next step if it isnt normal.

Swap injectors 2 - 4 and 6 - 8. See if the problem follows the injector or stays at the cylinder.

Compression check the cylinders.

Phonedawgz, I used a wiring diagram for connection of injectors off from this site. Do you know if there are different variations of where each injector is connected to the control module? I will have to give your test method a try, daughter has track meet today so it might be a couple of days.

Any OBD1 scan tool (Not just a code reader)*** should be able to interrogate and read the Caddy PCM.
You'll have to tell the scan tool that you're scanning whatever year Cadillac that your engine and PCM came from.

***phonedawg's solution is quite possibly more economical.

Start by checking at the injector connectors to make sure you have +12 on each injector connector (key on) on the Pink or Red or White wire. You can do this with the injector unplugged.

If you do have +12 on each injector then with the engine running read the voltage on the other terminal of the injector. You will need to do this with the connector still on the injector. To do this slip a pin down between the seal and the wire until it hits the metal terminal.

If on the non power wire of the injector you are reading battery voltage then the ECM isn't firing the injector. If you are reading a voltage that is about 4v less than the power wire of the injector then the ECM is firing the injector.

I have never seen a wiring diagram for a 16132240 that doesn't put the injectors on the same pins. My guess is you have a power issue if you have two injectors located next to each other that are not firing.

The check engine light might be from a error code P107 PCM/BCM Data Link Problem or just the loss of battery power to the ECM.
The caddy computer is looking for the BCM but it's not there. I can not figure out to get rid of this error message.
I am in the process of contacting stickpony to reprogram my chip.
My swap runs fine as long as I have my Tech1a scanner plugged in but that's getting old.

quote Originally posted by SERGE144: My swap runs fine as long as I have my Tech1a scanner plugged in but that's getting old.

That is odd, the engine will run just fine without the reprogram - although it is far from being optimized. You may have an issue there.