4.9l V8. Where is ECM located? - 1991 Cadillac DeVille

If I'm not mistaken, GM has had the voltage regulator internal to the alternator for years before '93.
The alternator has to be disassembled to repair the voltage regulator. Most do-it-yourselfers just replace the alternator.
Here's a picture that shows the regulator at RockAuto -

1993 CADILLAC ELDORADO 4 9L V8 Voltage Regulator RockAuto

Hello Jamie Pickett,

External to the ALTERNATOR there is indeed a
"Generator Disable Connector" showing
advance of the (onboard) REGULATOR.

FREE Factory Drawings are available at
BBB Industries at (registration required)

BBB Industries Premium Alternators Starters Power Steering Products
Look under Engine, electrical: charging.

Parts
http://www.rockauto.com/en/catalog/cadillac,1994,deville,4.9l+v8,1025772,electrical-connector,alternator+/+generator+connector,2528

Hope this helps

Carnac the Magnificent

1994 CADILLAC DEVILLE 4 9L V8 Alternator Generator Connector RockAuto

The ECM is located behind the drivers side or pas side kick panel

Hello Jeff Winner,

Over the last 20 years ... cars have has a LIMITED OPERATION FEATURE added... When the engine READS something that is not IMMEDIATELY catastrophic... it will allow you to
LIMP home... rather than a complete shut down.

Limp mode:
You SHOULD also have a CHECK ENGINE light... (?)

My best advice is to limp on down to your near-by FREE code reading shop... and have a READER tell you what CODES are registered...

A blocked exhaust system will also seriously SLOW your progress
((soon to stop all-together)).

Hope this helps

Check you exhaust prices BEFORE you go...!!

http://www.rockauto.com/en/catalog/dodge,1998,durango,5.9l+v8,1314473,exhaust 1998 DODGE DURANGO 5 9L V8 Catalytic Converter RockAuto

1998 DODGE DURANGO 5 9L V8 Muffler RockAuto

Hook it up to a code reader via OBDII for specifics. Tecnically, there is no reason to flash your ECM unless you are using another ECM from a parts car...for say a 1989 Chevy. This ECM was used on the 1989 S-10 truck with the 2.5L four cylinder, the ’89 Camaro with the 5.0L HO V8 and the ’89 Corvette with the 5.7L Tuned-Port V8 engine. The only difference (aside from the vehicle wiring harness pin population) was the PROM. The PROM contains the calibration software for the ECM. Another reason would be to bypass a security locked ECM like a 2001 Pontiac GT which was notorious for shutting off the fuel pump if the security chip in the key lost connection through switched power.

Chris, Check the attached links,instruction, diagrams and guides for your caddies cooling system. Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
1992 Cadillac Eldorado 4 9l cooling system diagram Google Search

Parts com Genuine Factory OEM 1992 Cadillac Eldorado Touring V8 4 9 Liter...

1992 Cadillac Eldorado Parts GM Parts Online GM Parts Direct

Likely Coolant Leak Locations General Cadillac Forums

Dodge Ram 1500 5 9L Thermostat Removal Part 1 - YouTube

? 9:26
www.youtube.com/watch?v=eo6VW-wtGus
Aug 27, 2012 - Uploaded by RatchetsAnd Wrenches My Dodge Ram 1500 with a 5.9L engine had an over heatingissue which I was able to narrow down to the ...

Engine Control Module (ECM) (LD8/L37)
Front left side of the engine compartment, inside the air cleaner housing.
Transmission Control Module (TCM) (LD8/L37)
At the left rear of the engine compartment, on the strut tower
They call it a PCM when TCM an ECM are all in one module. You have ECM an TCM

side of your throttle common fail .try on ebay for one you must replace the full body not just that part.

its built into the ecm located right in the middle of he firewall from under the hood, big black box with two plugs.