Won't start - FFCars.com : Factory Five Racing Discussion Forum

John "jonjenids" · 03-04-2008, 01:55 AM

Here's the details. 4.6 DOHC 99 Cobra, Detail Zone wiring harness. I have power to all connections. The data port will not talk to the ECM. Diagnostic tool reads NO LINK. Plug in a Preditor and it reads Does not recognize vehicle or does not read the key is turned on. I am not using the original key or gauges. Even if Pats is preventing it to start It still should read the data port. Checked all plugs, grounds, made sure power is reaching the ECM plug in. even checked wire continuity. Also my fuel pump(original) stays on when key is turned on even if the ECM is unpluged. HELP!!!!!!!!!!!!

90notchback · 03-05-2008, 03:05 AM

Have you checked to make sure the ECm is fully seated and the screw is fully tightned?

Starboy · 03-05-2008, 02:46 PM

I used the DZ and RF kit with my `99 Cobra 4.6 DOHC. Have you called the DZ guys? They were great to work with on sleuthing out issues I had.
It's been a while since I installed mine and I never had the reading issues so I don't know how much help I can be but I'll try.
Inertia switch...is it popped out?
Did DZ flash your computer for you? I had them eliminate PATS, two O2 sensors, EGR, etc., but I don't think these would stop it from getting the reads.
Was the computer working when it was removed from the car? Was it stored in a good place so it didn't get knocked around real bad? It might be a bad computer.
I had some fuel pump issues and they resulted in a few grounding issues, but DZ helped me walk through a few checks and we easily found them and it all worked out.
You mentioned that you checked all the grounds and that is usually the major culprit when dealing with the wiring woes.

Don't worry....I know it can be frustrating...you'll get it worked out.

Keep posting..particularly if you get it worked out.

Don

James88 · 03-05-2008, 03:56 PM

Sounds like the ECM is not getting power or has failed. It's probably power. Start with the little things: are the fuses for the ECM installed, and if they are, are they good? Don't judge them by how they look, use a multimeter and ohm them out.

Then see if you can find the wires on the connector to the ECM that supply power to the ECM, and use a meter to see if the voltage is present. DZ can probably tell you which ones to check. If the power is not present, find out wjere it comes from and check it there. If it is present at the source, but not the connecter to the ECM, you likely have an open wire.

Also try and find out if there are test points on the ECM you can check to see if is getting the power. Again, DZ probably has the answer on that.

If you have power to the ECM, then the ECM may have failed. But before you toss it, check the circuit board. Look for loose EPROMs, they often contain the program tht runs on the ECM, and if they are loose it will make the ECM just sit there and do nothing.

Good luck.

Jim Snover

Quote:

Originally Posted by jonjenids

Here's the details. 4.6 DOHC 99 Cobra, Detail Zone wiring harness. I have power to all connections. The data port will not talk to the ECM. Diagnostic tool reads NO LINK. Plug in a Preditor and it reads Does not recognize vehicle or does not read the key is turned on. I am not using the original key or gauges. Even if Pats is preventing it to start It still should read the data port. Checked all plugs, grounds, made sure power is reaching the ECM plug in. even checked wire continuity. Also my fuel pump(original) stays on when key is turned on even if the ECM is unpluged. HELP!!!!!!!!!!!!

John "jonjenids" · 03-06-2008, 04:11 AM

Thanks for all the checks, its looking like the ECM has failed. I Borrowed a buddies tonight to see if my Data Port would talk to his ECM and it did. So it looks like my wiring is ok . I did check power all the way to the ECM plug in and that was good. Just keeps pointing to the ECM. Can they get reflashed or do I need a new or different one ? DZ has been a great help we just kept hitting dead ends, even he was getting stumped.

Domino · 03-06-2008, 12:13 PM

Sounds like it is time to see the junkyard or go to O'rielly's auto. If you go the junkyard route, be sure to get at least a 30 day warranty so you can swap it if you run into the same problem. O'rielly's can get reman pcm's I think they average around 175.00 but will come with a longer warranty period and the added convienence of not having to search around.

Dave

John "jonjenids" · 03-07-2008, 04:42 AM

I guess its time to start looking for a ECM. thanks for the help will let you know if it works.

John "jonjenids" · 03-08-2008, 02:28 AM

I hate to ask this and sound stupid but what is EPROM and does the stock ECM have a chip in the opposite end of the pinned plug in ,behind the black plastic snap cover ? Ford can't even answer that one.

James88 · 03-15-2008, 12:33 AM

Not dumb questions at all. EPROM= electronically programmable read only memory. It is the chip that stores the program the PCM uses to run the egine and manage the vehicles other features like anti-lock brakes, etc. When you see folks selling performance chips, this what they are talking about. It takes special equipment to program/re-program an EPROM, and unless yo uknow what you are doing, it is not a task lightly attempted.

Chips are not usually plugged directly into the back of connectors. Designers like to have one section of the board terminate the connector, and have individual wire runs in the board to bring power, signals, etc, to/from the chip. EPROMS are often mounted in special sockets that allow the EPROM to be removed and another put it in it's place. But sometimes they are not.

I can't say for sure how Ford mounts theirs. But tell us the year and model of vehicle you got the ECM from and I bet someone here can tell you which it is.

Jim Snover

Quote:

Originally Posted by jonjenids

I hate to ask this and sound stupid but what is EPROM and does the stock ECM have a chip in the opposite end of the pinned plug in ,behind the black plastic snap cover ? Ford can't even answer that one.

John "jonjenids" · 03-16-2008, 03:35 AM

the year is a 99 mustang cobra 4.6 DOHC and the ECM came with it . Its funny no one has been able to answer if the thing has a chip from the factory or just a port for performance chips. Anyway I ordered a new ECM from Max at ford, should come soon. let you know what happens. By the way when getting a new ECM ford says it has a basic program in it to at least start the car but it needs to go to ford to basically finish the programing. can't I just program it with a predator and not go to ford ?

James88 · 03-16-2008, 08:26 PM

Yep, there is a chip in there, from the factory. It will have to be removed for the new chip. Yes, you could program it yourself with an aftermarket tuner as long as that tuner supportsthat year model of ECM. The only exception to that would be if Ford has started putting in some sort of "crippleware" to prevent anybody but Ford getting your money. I have not heard of them doing anything like that, but these days many manufacturers are starting to do exactly exactly that, and with programmable devices it is all too easy to do.

Jim Snover

Quote:

Originally Posted by jonjenids

the year is a 99 mustang cobra 4.6 DOHC and the ECM came with it . Its funny no one has been able to answer if the thing has a chip from the factory or just a port for performance chips. Anyway I ordered a new ECM from Max at ford, should come soon. let you know what happens. By the way when getting a new ECM ford says it has a basic program in it to at least start the car but it needs to go to ford to basically finish the programing. can't I just program it with a predator and not go to ford ?

John "jonjenids" · 03-18-2008, 04:14 AM

Got the new ECM today. plugged in the Predetor and it read the stock tune then I downloaded the new tune. Tried to start, wouldn't start. looked up trouble code, said fuel pump module. This is my first experience with these things. If these computors tell you whats wrong are they pointing to the exact problem. Do I need a new fuel pump mod.?

John "jonjenids" · 03-18-2008, 04:37 AM

Just read up on the search about fuel pump modules. I just remembered the module won't stop running even if the ECM is unplugged. does this sound like a short somewhere ? I did find a broken ground in the fuel pump wire and fixed that because at that point the fuel pump wouldn't even run, and now it won't stop running. Theres gotta be a happy medium in there somewhere.

James88 · 03-18-2008, 11:21 AM

Yes, that sounds like a dead short. It absolutely should shut off.

Jim Snover

Quote:

Originally Posted by jonjenids

Just read up on the search about fuel pump modules. I just remembered the module won't stop running even if the ECM is unplugged. does this sound like a short somewhere ? I did find a broken ground in the fuel pump wire and fixed that because at that point the fuel pump wouldn't even run, and now it won't stop running. Theres gotta be a happy medium in there somewhere.

John "jonjenids" · 03-19-2008, 03:55 AM

What is a "dead" short ?

James88 · 03-22-2008, 03:21 PM

Sorry, more electrical jargon. A dead short is when you have a wire that is going straight from a battery or other supply to ground. It's a "short" circuit, because it bypasses the rest of the intended cicrcuit, and it's "dead" because it usually kills the battery or the power supply because it makes a much higher load on them than the intended circuit. An example would be the positive lead from a battery to the starter that has had its insulation worn away and is now touching the frame.

A short can happen anywhere in a circuit, even bypassing certain compenets of a circuit, such as the ignition switch which supplies and cuts power to the fuel pump, in your specific case. So the fuel pump always runs because the switch has been dead shorted, eventually killing the battery.

I bet you wish you had not asked, now.

Jim Snover

Quote:

Originally Posted by jonjenids

What is a "dead" short ?