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Discussion Starter · #1 ·
MANY PEOPLE HAS SUGGESTED:
A-PULLING OUT THE (-)NEG CABLE
-THEN PRESS ON THE BRAKES FOR 5 SECONDS
-THEN REATTACH THE (-)NEG CABLE
-THEN START THE CAR AND LET IDLE FOR 5 MINUTES

OR

B-PULLING OUT THE (-)NEG CABLE FOR 5 MINUTES
-THEN REATTACH THE (-)NEG CABLE AND LET IDLE FOR 15 MINUTES

SO WHICH WAY IS WORKS? OR DOES ANYONE KNOW THE CORRECT PROCEDURES?
 

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n4te33 said:
MANY PEOPLE HAS SUGGESTED:
A-PULLING OUT THE (-)NEG CABLE
-THEN PRESS ON THE BRAKES FOR 5 SECONDS
-THEN REATTACH THE (-)NEG CABLE
-THEN START THE CAR AND LET IDLE FOR 5 MINUTES

OR

B-PULLING OUT THE (-)NEG CABLE FOR 5 MINUTES
-THEN REATTACH THE (-)NEG CABLE AND LET IDLE FOR 15 MINUTES

SO WHICH WAY IS WORKS? OR DOES ANYONE KNOW THE CORRECT PROCEDURES?
Either will work. When resetting a PCM, all you're doing is removing power from it so the internal memory gets wiped on the next boot sequence when the processor detects a battery-backed RAM checksum fault. By waiting a few minutes, you give the capacitors in the PCM time to drain, ensuring the RAM gets no power; pressing the brake pedal can help to speed this process.

You really shouldn't need to let the car idle for 5 or 15 minutes after a PCM reset. Just start it as usual and drive normally. The PCM will re-learn those parameters as it sees a need to.
 

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mike,

On monday, i'm planning on getting my o2 sensors replaced. Is it a good idea to do this procedure after they are replaced? Also, since, I have the stock radio in the car will i have to go to mazda if i disconnect the battery because of the security feature?

thanks,

Anthony
 

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integrale4wd said:
mike,

On monday, i'm planning on getting my o2 sensors replaced. Is it a good idea to do this procedure after they are replaced? Also, since, I have the stock radio in the car will i have to go to mazda if i disconnect the battery because of the security feature?

thanks,

Anthony
No, you don't really have to reset the PCM following O2 sensor replacement. The PCM will adjust its internal trim values to suit the new sensors after a very short time in closed loop mode.

As far as the radio goes, I'll admit to being a bit fuzzy here since I have a Probe with the cheesy Ford radio in it which has no such security feature. If you really want to reset the PCM but not lose the radio codes, try pulling the ROOM fuse instead of pulling the negative battery terminal. That will disable the keep-alive power to the PCM and should cause a reset.
 

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Mike 94PGT said:
As far as the radio goes, I'll admit to being a bit fuzzy here since I have a Probe with the cheesy Ford radio in it which has no such security feature. If you really want to reset the PCM but not lose the radio codes, try pulling the ROOM fuse instead of pulling the negative battery terminal. That will disable the keep-alive power to the PCM and should cause a reset.
Pulling the room fuse will also disable the radio. It is the same fuse that suppolies constant power to the radio as well. If you have never activated the code fro the radio there is nothing to worry about, but if you don't know if it has been activated then you might want to see if you can find the code before doing this.
 

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From what i have heard...you have to pay for the code too. I think that is ridiculous...but anyhow...I'll see what happens.

thanks,

Anthony
 

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I reset my ECU every time I work on my car, whether I have to or not. I am going to tackle my rear sensor this weekend and am not going to reset it per Mike's comment and save myself 15 mins. of radio re-programming. Yes Mazda does charge for unlocking the radio. Got rid of that problem, with a Sony detachable face. :D
 

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hello,

I got rid of the right and left o2 sensors...i payed 250. I didn't reset computer...we just let it idle for a few minutes.

Anthony
 

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So does resetting the ecu mess up the stereo security codes? I was thinking about resetting mine cause i just got a new exhaust, but i dont wanna be with out my stereo and i definitley dont wanna have to pay to fix it. Whats the real deal?
 

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hello,

it doesn't mess up the stereo codes...you will have to go to mazda to get the code punched in for you to use the stock stereo(it might cost you 30 dollars or so)...as a matter of fact...I'm just going to put a stereo system in there.

take care,

Anthony
 

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what f***ing rip off. Im not gonna pay mazda to fix something that aint broke. Is there anyway i can do it myself?
Wasn't someone complaining about not having a mazda radio? I gladly take a wonderful Probe GT at this point

We owe our Probe members and friends some respect.


[Edited by xeon on 03-13-2001 at 11:01 PM]
 

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MX-6 BOY jr said:
Mike,

wouldn't you want to reset the compter after changing the o2 sensors to get rid of the ecu codes?

You could but it's not absolutely necessary. The only time a "code" is actually active and possibly affecting the operation of the PCM/engine is when the check-engine light is actually illuminated. When the light is out, the PCM is running as normal. The stored codes are just that: stored as a history of something that has happened, but isn't necessarily happening now.

So if you change the O2 sensors, the PCM will quite happily see the O2 sensors as functioning nominally and will execute the "normal" logic, even if codes for the previously-bad O2 sensors are still socked away in NV RAM. The codes stored in memory will not affect the running of the PCM.

Erasing codes is good practise of course, because it makes determining which of any new codes that show up after the work is done are "real" and which are simply from before the work (if that makes sense...) For example, you change the O2 sensors but don't erase the code(s). For a month, you never see a check engine light. Then one day, the light comes on and you read the codes out. You get, say, a code 16 and a code 17 but aren't sure now if the 17 is still there from a month ago or if it was involved in the CEL coming on just recently.

So for you Mazda guys with radio codes to worry about, you can save the code-hassle by not erasing the malfunction codes at all and not suffer any ill effects.

Of course, the OBD-II fellows can erase the codes through the J1982 port via software commands issued via scan-tool, never having to disconnect the battery :D
 
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