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Old 09-24-2018, 12:17 AM
  #1  
MattGT01
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Exclamation PCM help

I installed a salvaged PCM today to replace mine in my 2003 Mach 1. I have a few questions I'm hoping someone can help me with...

1) My car started up right away, no issues. Everything I read said I had to get it "programmed" or "flashed" before it would start, and so it would match my keys. Do I still need to do either of those since it's starting up with no issues?

2) I plugged in my 'Carmd' post install, and it read out the same errors as my previous PCM. Is that even possible? Could it just be the carmd already had the errors stored and since it's not the best tool it didn't read anything new?

Thanks for all the help. I've dealt with the "Catalyst Monitoring" pretest always being in "not complete" even though I've driven thousands of miles and followed Ford's guidelines to a T on completing the pretest, so I can't get my Mach to pass smog since it's always "not ready to be tested." A shop recommended replacing the PCM so I'm hoping this will fix the issues.
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Old 09-24-2018, 02:01 AM
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Stepman
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If it still reads the same issues, it wasn't the pcm that was bad. I'm guessing that you disconnected the battery when you changed but, even if you didn't, it lost power when it was disconnected which erases any codes stored. I'd put the first one back in and go from there. What is the issue, codes you are having?
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Old 09-24-2018, 02:10 AM
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08'MustangDude
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Your PATS unit is not the ECU, so the keys would work. The ECU flash would only
be so the VIN in the ECU matches the car.

If the CEL was on, and CarMD read the codes, then yes, it would be the same
issues if there are bad sensors and what not.

IF you turn the key to RUN, and wait 13 or so seconds, if the CEL flashes, then
it is not ready for emissions testing. You don't need a code reader to find that
out. My '08 does it right after I tune it, so did my Charger....

If you still have codes, then it won't complete the pretest, especially if they are
02 sensor related.
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Old 09-24-2018, 12:38 PM
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MattGT01
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Thanks for the replies...
Originally Posted by Stepman View Post
If it still reads the same issues, it wasn't the pcm that was bad. I'm guessing that you disconnected the battery when you changed but, even if you didn't, it lost power when it was disconnected which erases any codes stored. I'd put the first one back in and go from there. What is the issue, codes you are having?
Correct, the battery had been disconnected for a week. What's interesting is after I put in the new PCM and started it, I immediately connected the carmd, didn't drive it at all, not even around the block. Doesn't it need to be driven a little to register any codes?
My CEL is not on, has never been on, and the two codes are the exact same as my original PCM: C1805 (Mismatched PCM and ABS) and b1869 (air bag indicator light). I've heard C1805 can occur because my rear tires are a different size. Maybe that's why the shop told me to change my PCM, because it says mismatched, even though the original one was in it.

Can either of those codes prevent the "Catalyst Monitoring" pretest from not completing? That's the only one that won't finish.

Originally Posted by 08'MustangDude View Post
Your PATS unit is not the ECU, so the keys would work. The ECU flash would only
be so the VIN in the ECU matches the car.

If the CEL was on, and CarMD read the codes, then yes, it would be the same
issues if there are bad sensors and what not.

IF you turn the key to RUN, and wait 13 or so seconds, if the CEL flashes, then
it is not ready for emissions testing. You don't need a code reader to find that
out. My '08 does it right after I tune it, so did my Charger....

If you still have codes, then it won't complete the pretest, especially if they are
02 sensor related.
When I turn my key forward (what I assume you mean by RUN) my CEL is illuminated constantly, does not flash. When the car is started, my CEL is not on - it wasn't with the original PCM and isn't either with the new one.
The two codes are the exact same as my original PCM: C1805 (Mismatched PCM and ABS) and b1869 (air bag indicator light). I've heard C1805 can occur because my rear tires are a different size. Maybe that's why the shop told me to change my PCM, because the code says mismatched, even though the original PCM was in it.

Can either of those codes prevent the "Catalyst Monitoring" pretest from not completing? That's the only one that won't finish.

Thanks again for the help
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Old 09-24-2018, 01:51 PM
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08'MustangDude
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For C1805, both the CEL and ABS light will be on. If they are not on, then they're
not set in the ECU. I would have to assume that the data is still in the software
memory storage, since you did not clear it before replacing the ECU.

B1869 is ABS light open circuit, which can mean the bulb is out or bad connection, bad module,
or the bulb harness is open or shorted. The air bag light is designed to illuminate for 6 (±2)
seconds when the ignition switch is turned to the RUN position. This initial 6 seconds of
illumination is considered normal operation and is called Prove-Out of the air bag indicator.
SO, if you turn the car on, and the light is on, and then goes out, then it's not your ECU or
MODULE, would assume it's stored from last ECU.

So. basically, if you have no MILS, then it's not live information.

You can also have no CEL for the not ready condition, and be O2 sensors:
An O2 sensor voltage above 0.45 volts is interpreted by the ECM as a rich exhaust, and an
O2 sensor voltage signal below 0.45 volts as a lean exhaust. The rear oxygen sensor should
be producing a steady stream of .45 volts (approx.), indicating the catalytic converter is doing
it's job. You will need a tool to be able to read the live data from the sensors once the car
is at full operating temperature.

You can use a digital multi-meter and test the oxygen sensors directly.

The fuel tank between must also be 30 and 70 percent full. Some systems, especially the Evap system,
need to have a specific level of fuel in order for the tests to be trusted. The vehicle must sit overnight, or for at
least eight hours, in an environment that is less than 90° F before the cycle us run. Also, if the battery is weak
or undercharged, some of the most important tests will never run.

If it's the cat o2 codes that need to be cleared try accelerating from 40 to 60 very gently, and then letting the speed
drop back to 40 without using your brakes. Do this 5 times in succession and see what happens.

Ford says If the oxygen sensor and catalyst monitors are also not ready, the culprit is most likely a weak battery.

If you have an aftermarket intake, return to stock to run the cycle.

ANY time you reset the ECU, by power, or clearing codes, the drive cycle needs completed.

The Ford drive cycle required to run the Catalyst Efficiency Monitor involves driving your Ford Mustang
in stop & go traffic conditions. Include five different constant cruise speeds, ranging from 25 to 45 MPH
over a 10 minute period.

You may need to go to a dealer to have the monitors turned on, if for some reason that
ECU has them off, and it just could be because of the swap; VIN mismatch.









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Old 09-24-2018, 06:49 PM
  #6  
MattGT01
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Thanks for the extensive reply. A few questions / comments

1) If I have codes but no CEL illuminated, does that mean there is an issue with the memory storage? I figured that would have been wiped out when I replaced the ECU. How else do I clear the storage and essentially start from scratch?

2) Yes, my ABS does light up in the RUN position

3) When you say ‘no MILS, no live info’ where is that info stored? Relates to question #1, can I wipe that info and see if it won’t replicate with the new ECU?

4) O2 Sensors: Could any smog repair place check the volumes? I don’t have access to a digital multi-meter and I think that’s above my head mechanically

5) I’ve done the Ford drive cycle probably 500 times J because that’s what every smog station tells me to do. They plug it in, car says ‘not ready’ (because of the Catalyst Monitoring pretest) and then they say to go drive it for another 100 miles and go through the drive cycle.

6) I have a brand new battery

7) Stock intake

8) As for the monitors being turned off, as I said before I didn’t even drive the Mach after putting in the new ECU and it immediately spit out the same codes as the original ECU, so I would rule out VIN mistmatch since the issue was present before

9) Back to my original question – The two codes I’m getting, do you know if they’d have anything to do with ‘Catalyst Monitoring not ready’ ? They don’t seem like urgent codes, based on my research, so I don’t want to spend the time fixing them first when there could be a higher priority (O2 sensors)



Sounds like my action items are

- Have a shop test my O2 sensors

- Learn how to ‘clear data storage’ and start fresh to see if the current codes come back

- Find out if the two codes I’m getting could cause the ‘not ready state’



Anything else you can think of? I appreciate your time, let me know if I can paypal or venmo you a donation for your effort.
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Old 09-25-2018, 06:03 AM
  #7  
08'MustangDude
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MIL = Malfunction Indicator Light.

Even if the CEL is not on, you can clear DTCs (codes) and run the car again, see if they
return. Some of them need cleared before the emissions devices can become ready, even
if they are working. Federal law REQUIRES the CEL to illuminate if there is an emisions
related failure. Monitor not ready is not one of those conditions to set the CEL.

Use your device to "Clear DTCs" and see if they return.

The ABS module is separate. That MIL is set for various reasons, so you need to see why. The ABS module
is setting the C1805. ABS Light is common when the front and rear tires have a different diameter. B1869 code
being set as well, may just indicate the ABS module is no good.

These can effect readiness.
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Old 09-25-2018, 08:26 AM
  #8  
Stepman
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Iwonder if these codes could be coming from the air bag module. I can't remember how to do it but, look into reading and clearing the codes from that. I believe its done with a paperclip on a connector behind or under the glove box. I believe the cat not ready will be a dead o2 behind the cat or a bad cat. Maybe just not getting up to temp.
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Old 09-25-2018, 03:41 PM
  #9  
08'MustangDude
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Just in case you need it...


There is no actual reset, that is done by removing power from the ABS module,
but they want you turn the car to RUN, do not start, then pull the negative
battery cable. However, you did this when you put the other ECU in, so the
fault is still in the ABS module.

ABS TESTING:
http://ww2.justanswer.com/uploads/MA...npoint_abs.pdf
CLEAR the DTCs.
RETRIEVE the DTCs.
If DTC C1805 is retrieved, check the PCM and the ABS module is for the correct vehicle.
INSTALL a new PCM or ABS module as necessary.
CLEAR the DTCs.
REPEAT the self-test.

DID you get a '03-'04 Mach 1 ECU? You cannot use one from a NON Mach 1 car. The
ECU programming is different, because the Mach 1 has 305 horse power, a GT is 260 HP.
The readings from the emissions equipment on the Mach 1 will not be within SPECs on a
GT ECU, so it may never become ready for testing. The Mach 1 was only available in 2003
and 2004, you cannot use any other ECU than a Mach 1's ECU. Just stating this, just in case.

While, you can use almost any 01-04 V8 ECU, you need one from a Mach 1.

The Mach 1 it was re engineered with a free flowing exhaust and intake manifold to increase the engine by 30 horsepower.
Free flowing exhaust is the key here, if you used a Non Mach 1 ECU.

Just covering all bases...
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