Hey all, another question as I continue to try to resurrect my 1982 Firebird (5.0 carb). My CEL is always steady lit, even when jumping ALDL for diagnostic mode, no code 12 or any other flashes. Found a few threads that led me to believe it was the Lamp Driver Module, so I ordered a replacement off Amazon which arrived today. Plugged in the new LDM, and the light is now just off. It won’t flash when jumping for diagnostic mode. What am I doing wrong here? I ordered SMP RY-536, but the part that arrived looks different than the picture (they included a note that it may look different but would function the same). Do I need to order from somewhere else? As far as I can tell, there’s nothing else that could be causing this problem. Any help is appreciated!

 

Does the CE light work normally under regular circumstances ?? Turn Key,...... CE light ON. Start car,... CE light OFF ?

Are you JUMPING terminals "A" & "B" of the ALDL with a wire / paperclip to check your codes ?? ( as per the 83 shop manual )

I've got a Lamp Driver in my hand and it's got the same PN on it as what you bought. "12020004". Ya', It does look a bit different. There are 5 traces to the plug,... but only 4 of them get used. The one you bought has 6 traces for the plug.

The CE light gets power from the gauges ( or IP) fuse on the PINK/Black wire. When the ground circuit to the CE light is 'open' the light is not lit...... when closed (grounded) the CE light illuminates. That means that when you turn the key to RUN the CE light is getting ground thru the yellow wire; when you start the car the ECM should send a signal to the Light Driver to remove ground from the YELLOW wire.

I assume the WHITE ( or WHITE/Green ) wire from the ECM to the Lamp Driver is what should also signal the Lamp Driver to give/take ground from the YELLOW wire (ECM light) to show the codes.

What's to say the ECM wasn't also a problem ??

 

The light stays on in normal circumstances, key on or while running. Yes I am jumping terminals A&B with a paper clip. Here are some photos of the Lamp Driver (the one pulled out of the car, the one that was delivered, and the picture from Amazon) so I’m really confused by that. Maybe you’re right that it’s the ECM. Either way, I think I can assume that the Lamp Driver they sent me is not going to work since it only made the problem worse.

 

Do you know your ECM PN ?? 305 LG4 / Auto ?

 

Hi 1982MSE47 ,

Don't let the different appearance of the new unit worry you , your original unit was built with the technology of the 1980s , when the physical size of the components was still quite large . With the modern day invention of "Surface Mount" components that come in much smaller packaging , yes I know it looks vastly different at a quick glance , but upon a close look you can tell that both boards contain the exact same components ; one Transistor , one Diode , one capacitor , and three resistors .

The new unit could be defective , or as John said it could be the ECM or it's wiring , but just the fact that it looks different isn't an automatic conclusion that it's the wrong one ....

 

I replaced the ECM with one off ebay (switched my PROM over first) and no dice, the CEL is still staying lit constantly, won’t flash codes with paper clip. You said it could be a wiring issue? I did confirm the ECM was getting power from battery and ignition with multimeter. Anything else worth checking? Thanks for the help!

 

Check the connection from the ECM to the driver, the white/green wire, and verify that with the driver module plugged in, it goes from logic high (probably around 5V) when the light should be lit, to near ground when it should be off. Verify that it does the same thing at the ECM plug, pin G of C232.

 

If your original PROM was the problem,............... ???

Your Check Engine light is acting as if the ECM isn't connected at all. Here's the schematic for the 83 Camaro Check Engine Light. I'm GUESSING that your 82 will be similar.


While the car is running: Probe PIN 'C" of the C207 connector with test light or voltmeter and check for ground. If there are no trouble codes the ECM should be grounding C207 PIN 'C' ( or PIN 'G' on ECM connector) when the engine is running. If there is no ground than there is a trouble code stored,.... or the ECM/PROM/Wiring is suspect. If there is ground then the Lamp Driver / wiring is suspect.

With the ECM disconnected & car off, turn key to RUN ( not START! ) & apply ground to PIN C of the C207 Dash-to-ECM harness connector. ( or PIN 'G' on ECM connector ) If the Check engine light goes off then the new Lamp Driver is probably OK and the problem is the ECM, PROM, or wiring. If the Check Engine stays lit then the Lamp Driver is suspect. ( verify battery power on PINK/BLACK and GROUND when key is turned )

Here is the troubleshooting flowchart for the 83. ( I ASSUME that 82 is similar )

 

Thanks for all the help! I’m now flashing code 12! It also gave me a code 51 for a PROM error. Where would I get a new one, everything I’m reading here says they are specific to the car? It’s a 305 carbureted, auto trans.

 

Disregard. Future readers, make sure your PROM is plugged all the way in before you make yourself look like an idiot like I just did

 

Glad to hear you got your ECM working again !

* I've found Lamp Driver Modules in Carb and Crossfire cars,... it was not used in any V6 or V8 fuel 'injected' Thirdgens.

 

Having the same issue you were with my '82 SE, same engine. How exactly did you fix this? Amazon driver module just turned light off and OEM module doesn't kick into diagnostic mode, light stays on. Help would be much appreciated