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Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Cadillac
Satisfied Customers: 3831
Experience:  Owner at Carolina Auto service & Sales , 20 years Experience in Foreign & Domestic vehicles
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Changed out the old EMU of a 2003 Cadillac CTS. It was

Customer Question

Changed out the old EMU of a 2003 Cadillac CTS. It was programmed from the manufacturer i gave them the vin # ***** part number. dash board has the check engine light on so i know its hooked up right. I turn the key and it does nothing but flash the dash board lights. I see the anti-theft light comes back on.. I re-installed the old CMU and it cranks but wont start. Like it was before.
Ive tried the on for 10 mins 3 times but the anti theft light never goes off. Im at a lost what to do next except going the the dealership to test the new CMU? Help what am i missing ?
Submitted: 1 year ago.
Category: Cadillac
Expert:  Chad Farhat replied 1 year ago.

Hi my name is ***** ***** I will be assisting you today

Customer: replied 1 year ago.
Not sure whats going on with this new EMU.. its like the battery isnt hooked up outside of the dash lights
Customer: replied 1 year ago.
maybe the Anti-theft isnt letting the engine turn over
Customer: replied 1 year ago.
Expert:  Chad Farhat replied 1 year ago.

hey sorry for the delay man I just logged back in

Expert:  Chad Farhat replied 1 year ago.

If you tried the master reset 3 times and did not fix it ,than we have an issue the anti theft system , it could be your cmu but it also it can be several other things , if you take it and get scanned & retrieved the codes and let me have them i can then tell what you need, the most common is the cmu but not always , sorry for the delay , been having problem with internet connection since this morning i could not log in .

Expert:  Chad Farhat replied 1 year ago.

you have a problem with emu you got or that was not the issue with it, why did you chnage the emu ,did you check that was the problem all security sensors report back to antitheft module so if you read it you will know what is causing it from the codes , it might not be exactly where but will give us a place to start , because right now we just guessing , I m sorry it hard for these new system to figure out by visually looking , the reset does work sometimes but not in all cases unfortunately , get read and let me know i will help you with it , i dont want to tell you change this or that i just dont have enough info to give you the right diagnostic without codesa I will be guessing and i dont want to do that .

Thank You ***** ( aka -Customer)

ASE Certified Tech

Customer: replied 1 year ago.
on the master reset. I've seen two different things wait 10 mins and the anti-theft light goes out (which never does on mine) .. does this matter ?
Expert:  Chad Farhat replied 1 year ago.

well that means it is a hard fault in the system as soon as you hook up battery the system is armed, the key from reset is to clear the anti theft module and actually all car module and reset everything , usually that works if you went out of town for 2 month and battery died the alarm trigger from low voltage and then when u disconnect & charge your battery and hoook up battery again the alarm see the 12 v it needs and the security light will go out after few secs from you turn key from off to on or start , now yours is seeing the 12v and there is something else causing it to trigger since good battery exist in your case .

Expert:  Chad Farhat replied 1 year ago.

you can get me the codes and we can try to figure out , but all these module you will need a dealer to program if you dont have one to do that with ,so even if i told you which one after you scan it you still need dealer .

but we need those codes and then I can help you further , but the scan here is essential to troubleshoot the problem

Hope I was helpful to you , please let me know if you need anything else

A Positive rating is Much Appreciated

his Post Will Stay Open Even after You Rate Me For You To Come Back And Ask Me Anything Follow Up Questions You May have On This Issue.

Thank You ***** ( aka -Customer)

ASE Certified Tech

Customer: replied 1 year ago.
just bought the car it did not have a battery in it been sitting for at least 6 months without it. cmu went bad so they parked it
Expert:  Chad Farhat replied 1 year ago.

well it could be that you have an issue the cmu given by dealer , scanning it will confirm that , it will show if the pcm seeing the cmu , then you will know if is it a bad cmu or we are hunting something else , like a shorted wire , because you will end up throwing parts at it ,