How to replace ECM 03 4.7l

Gruff511 · Apr 25, 2016

Okay so ive come to the conclusion my engine computer is fried after talking to some people with the same issue as me.
Now I've been looking for a used replacement ecm for my 03 4.7l 2wd auto but am not sure if i need a specific one or if any 03 4.7l auto ecm will work?
Some people said i can get a used one and out it in but other people have said i need to get it reprogrammed before i put a different one in? How true is this?
Btw im new to these trucks so im trying to find as much info as i can.
Basically i was driving the other day and out of nowhere the truck just shuts off and will crank but wont start back up. I have fuel pressure but no spark.all fuses and relays are good and only get a cel for evap

JAMMAN · Apr 25, 2016

So far looks like any 2003 1500 ECM from a 4.7 or a 3.7 will work... transmission specific. If you have an auto get one from an auto, manual/manual.

This is just from a quick internet search please check with a few others first.

JAMMAN · Apr 25, 2016

And I just found another site that says anything 3.7 or 4.7 from 2003 to 2007 should work, transmission specific. Most places want your VIN first (probably to make sure you have a 3.7 or 4.7).

Looks like it is going to be right around $160 remanned.

joepizuro · Apr 26, 2016

also make sure ECU ground is good!!!

Gruff511 · Apr 26, 2016

I guess ill just get a used ec and try it. A few guys in my area said they swapped the computer and it ran but it ran like **** or didnt run so they had to get it reprogrammed. Not sure where theyd do that at but i have no other options.

Ive check every sensor and replaced them and traced all wires everything is still good. Everyone in my area says it has to be the ecm.
If its not the ecm then ill probably be giving the truck away.
Does anyone know what else could cause the motor to not start?

JAMMAN · Apr 26, 2016

Cam sensors are cheap and easy to replace and a bad one could keep it from running. It usually throws a code though.

Without looking at the truck hard to tell. Wish I had more, if you were in the neighborhood I'd throw it on the scanner.

Gruff511 · Apr 27, 2016

Ive replaced the cam and crank and map sensors. Im not throwing any codes though

Gruff511 · May 2, 2016

Okay so i tried a known good ecm and also tried one off my dads truck which is the same year and engine and everything. Still just cranks. Doesnt even try to start or anything.
Its been months now ive gone over everything i have no idea what it could be now. Everyone said it had to be the ecm but its not.
The only cel code im getting is 0038 which is for an o2 sensor but ive had that code long before the truck died on me and people said the o2 sensor wouldnt cause the truck to not start and run.

I really need some more opinions guys?!
Thank you

JAMMAN · May 2, 2016

Put the original ECM back in. Man I wish I could look at it.

I have never seen it happen but a misalignment between the drivers side cam gear and the crank tone ring might cause a no spark situation. This could happen if the timing chain was so loose it skipped a gear. You would have to point the crank balancer at TDC (just line the notch up with the marker) and take off the passenger side valve cover and see if the "V8" on the cam gear was at the top.

BUT before you do all that, if you are sure you have no spark (how did you determine no spark?) I would have someone handy with an ohm meter trace some wires. Perhaps something got pinched or a connector is rotted going in the bottom of your fuse block or a ground wire has rotted off to the back of the heads or the firewall. Something isn't lining up here.

Gruff511 · May 2, 2016

How many grounds are there? I seen one on the block to the body.another on the head going to the firewall and another ground from the battery to the body.all are good solid connections no rust.

I just looked at the bottom of the fuse box with all the plugs and they all look good. I just double checked all the wiring and it all goods as well i even removed alot of the plastic covering the wiring harness to see if i could see anything wrong with the wires but nothing.

If i were to connect an ohm meter to the ignition plugs what should it read? Because i thought only the ecm grounds the coils and theyre supposed to have constant 12v when running correct?

And yes i put the original ecm back in and i just picked up an o2 sensor to get rid of the CEL

This all doesnt add up to me as well. I guess my next step would be to check timing to make sure nothing happened to the timing chain..but i figured i wouldve heard something happen if it was the timing chain

JAMMAN · May 2, 2016

Yeah I'm not convinced on the timing thing just trying to think outside the box.

There is an ASD relay that goes to the coils and the injectors (you would still have fuel pressure just no squirt) AND in some cases the O sensor, According to page 323 in the service manual. See if you have power to that.

Terminals 85 and 86 are the power terminals. Measure the voltage to those, have someone turn the key on while you are looking at it because the pcm shuts it down after a few seconds.

IF you get no voltage then try each terminal to ground and have the person turn the key on and off. I don't know which is hot but you should get 12V between one of them and ground. The PCM switches the ground on and off to the relay, so if you get nothing between 85 and 86 BUT get voltage between whichever is hot and ground when the key turns to the running position then the relay isn't getting the signal. IF you get 12V between 85 and 86 when you turn the ignition to the run position then replace that relay.

I'm straining here LOL I could fix your truck or at least tell you what is wrong if I only had a couple hours with it.

Gruff511 · May 3, 2016

So i replaced both o2 sensors and still get code 0038. Could this be causing an issue with the no start?

Gruff511 · May 3, 2016

JAMMAN said:
Yeah I'm not convinced on the timing thing just trying to think outside the box.

There is an ASD relay that goes to the coils and the injectors (you would still have fuel pressure just no squirt) AND in some cases the O sensor, According to page 323 in the service manual. See if you have power to that.

Terminals 85 and 86 are the power terminals. Measure the voltage to those, have someone turn the key on while you are looking at it because the pcm shuts it down after a few seconds.

IF you get no voltage then try each terminal to ground and have the person turn the key on and off. I don't know which is hot but you should get 12V between one of them and ground. The PCM switches the ground on and off to the relay, so if you get nothing between 85 and 86 BUT get voltage between whichever is hot and ground when the key turns to the running position then the relay isn't getting the signal. IF you get 12V between 85 and 86 when you turn the ignition to the run position then replace that relay.

I'm straining here LOL I could fix your truck or at least tell you what is wrong if I only had a couple hours with it.

Yeah thanks for all the help man i really appreciate it..ill try that today when i get home.

Redtruck-VA · May 3, 2016

Your ignition, injectors and fuel pump have the same 12v power source (ASD relay). Does your fuel pump run when the ignition is first turned on? If so then the ASD relay is working. If it doesn't then look at the ASD relay as bad. If the ASD relay doesn't have 12v on it then look at the IPM having a problem. (corrosion)

Gruff511 · May 6, 2016

Redtruck-VA said:
Your ignition, injectors and fuel pump have the same 12v power source (ASD relay). Does your fuel pump run when the ignition is first turned on? If so then the ASD relay is working. If it doesn't then look at the ASD relay as bad. If the ASD relay doesn't have 12v on it then look at the IPM having a problem. (corrosion)

Yes i verified the asd relay is good and working..the injectors and fuel pump are working...

Im going to check the timing today. Some people said maybe the timing tensioner broke and created too much slack in the timing chain. Does that sound possible?

Redtruck-VA · May 6, 2016

Sorry I'm not familiar with 4.7's.

Gruff511 · May 7, 2016

Okay guys pretty sure i just figured out my problem. I pulled the front timing cover off and the passenger side timing chain guide is completely broken. And the tensioner is pusher directly on the chain.

So now my question is does anyone know where to get some good quality timing components? Like chain, tensioners, and guides?
Lol shoulda got a hemi...

Thanks for all the help everyone

JAMMAN · May 7, 2016

Excellent, really glad you found the problem.

Depends on how long you want to keep the truck. If you are in it for a year or 2 E-bay is your best bet. If it is going to be your daily driver for the next 5 years get something better.

If you have the money while you are in there get a high flow oil pump you will be just a few bolts from having it out during your journey. You will end up back in there replacing it eventually.

Depending on how much time you have and equipment on hand, if you drop the oil pan and pull the oil pickup screen, cleaning that plus the sludge in the windage tray plus cleaning the sludge in the back oil returns in the head (you will have to pull the valve covers) you will be good for 200,000 + if you never lost oil pressure and you keep up on the oil. You are in it this far might as well finish it if you have the money and time.

Gruff511 · May 7, 2016

Okay cool thanks..ill look into all that..is there a reliable site that sells good timing components for this motor? Have only had this truck for a year and plan on keeping it for probably another year or 2 more but will most likely give it to my younger brother later on so id like to make it pretty reliable. And yes this is my daily driver but i dont put alot of miles on it each day

Core-Lokt · May 7, 2016

RockAuto 4.7L Engine Parts

RockAuto is a good place to start looking. In the 3G General Discussion forum, I've got a post for an additional 5% off code and there might be some items with current rebates.

EDIT: Here's the code. 4493038136569961

How to replace ECM 03 4.7l

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