ECU for Jeep Cherokee

Hi,
does anybody know, if there is some programming or calibration to be done if
the engine control unit is replaced? Or do I just plug it in and thats it?
Thanks for the advice.

Jo

"reigelser" > wrote in message =
...
> Hi,
> does anybody know, if there is some programming or calibration to be =
done if=20
> the engine control unit is replaced? Or do I just plug it in and thats =
it?
> Thanks for the advice.

Big difference among the years, IIRC... I'm pretty sure
that all the modules have to agree on the odometer miles,
among other things, on mine. ECM, PCM, CCCM,
DRBII, DRBIII... alphabet soup.

On my '00XJ, buried way down on pg 14-1 Fuel Systems,
is the following:

PCM VIN REPROGRAMMING
OPERATION
USE THE DRB SCAN TOOL TO REPROGRAM
THE NEW POWERTRAIN CONTROL MODULE
(PCM) WITH THE VEHICLES (sic) ORIGINAL IDEN-
TIFICATION NUMBER (VIN) AND THE VEHI-
CLES ORIGINAL MILEAGE. IF THIS STEP IS
NOT DONE, A DIAGNOSTIC TROUBLE CODE
(DTC) MAY BE SET.

The way I read this, you can pop one in and it will
work... but your MIL (malfunction indicator light)
will illuminate, and I don't have a clue as to whether
it will ever go out. There should be some safeguards
preventing folks from resetting their odometers..
that's what this is all about. If you don't have a=20
digital odometer, chances are you've got the earlier
ECU, and can plug-and-go... it may take a few
start-stop cycles to learn all the operating parms
for your engine.

Why the new ECU, btw?
__
Steve
..

__
Steve
..

depends on the year starting in 04 all pcm,s are shipped with out software and
it has to progammed by vin
now more salvage yard pcm swapping
reigelser wrote:

> Hi,
> does anybody know, if there is some programming or calibration to be done if
> the engine control unit is replaced? Or do I just plug it in and thats it?
> Thanks for the advice.
>
> Jo

"tim bur" > wrote in message =
...
> depends on the year starting in 04 all pcm,s are shipped with out =
software and
> it has to progammed by vin
> now more salvage yard pcm swapping
^^^^^^^

One letter... how it changes things.
Tim probably meant 'no'...
__
Steve
..




> reigelser wrote:
>=20
> > Hi,
> > does anybody know, if there is some programming or calibration to be =
done if
> > the engine control unit is replaced? Or do I just plug it in and =
thats it?
> > Thanks for the advice.
> >
> > Jo
>

I need the ECU eventually because of a persistent TPS error. My mechanic
troubleshooted it and thinks its probably the ECU. But he thinks there has
to be some reprogramming to be done, because I tried one from the junk yard
before he looked into it and nothing changed (same TPS error, same mileage).
It's a 97 inline 6 Cherokee. It works, but it doesn't start at first try and
it is not very smooth if you want to accelerate from 65 to 75 without a
kickdown.

"Stephen Cowell" > wrote in message
...

"tim bur" > wrote in message
...
> depends on the year starting in 04 all pcm,s are shipped with out software
> and
> it has to progammed by vin
> now more salvage yard pcm swapping
^^^^^^^

One letter... how it changes things.
Tim probably meant 'no'...
__
Steve
..




> reigelser wrote:
>
> > Hi,
> > does anybody know, if there is some programming or calibration to be
> > done if
> > the engine control unit is replaced? Or do I just plug it in and thats
> > it?
> > Thanks for the advice.
> >
> > Jo
>

The TJ's ECU is known to be extremely reliable and just about
trouble-free. Have you already replaced the TPS and cleaned/reseated
the electrical connection that connects the ECU to the TPS? Bad TPSs
are easily replaced and far cheaper than replacing the ECU.

Jerry

reigelser wrote:
> I need the ECU eventually because of a persistent TPS error. My mechanic
> troubleshooted it and thinks its probably the ECU. But he thinks there has
> to be some reprogramming to be done, because I tried one from the junk yard
> before he looked into it and nothing changed (same TPS error, same mileage).
> It's a 97 inline 6 Cherokee. It works, but it doesn't start at first try and
> it is not very smooth if you want to accelerate from 65 to 75 without a
> kickdown.
>
> "Stephen Cowell" > wrote in message
> ...
>
> "tim bur" > wrote in message
> ...
>
>>depends on the year starting in 04 all pcm,s are shipped with out software
>>and
>>it has to progammed by vin
>>now more salvage yard pcm swapping
>
> ^^^^^^^
>
> One letter... how it changes things.
> Tim probably meant 'no'...
> __
> Steve
> .
>
>
>
>
>
>>reigelser wrote:
>>
>>
>>>Hi,
>>>does anybody know, if there is some programming or calibration to be
>>>done if
>>>the engine control unit is replaced? Or do I just plug it in and thats
>>>it?
>>>Thanks for the advice.
>>>
>>>Jo
>>
>
>

--
Jerry Bransford
PP-ASEL N6TAY
See the Geezer Jeep at
http://members.cox.net/jerrypb/

I replaced it allready and all voltages are fine in all ranges of motion of
the TPS. I also tried to disable other parts of the electric system to see
if there is an effect on the tps circuit, without success. The error won't
clear and there is still an effect on the driving behavior.
"Jerry Bransford" > wrote in message
news:kAore.88$X71.85@fed1read07...
> The TJ's ECU is known to be extremely reliable and just about
> trouble-free. Have you already replaced the TPS and cleaned/reseated the
> electrical connection that connects the ECU to the TPS? Bad TPSs are
> easily replaced and far cheaper than replacing the ECU.
>
> Jerry
>
> reigelser wrote:
>> I need the ECU eventually because of a persistent TPS error. My mechanic
>> troubleshooted it and thinks its probably the ECU. But he thinks there
>> has to be some reprogramming to be done, because I tried one from the
>> junk yard before he looked into it and nothing changed (same TPS error,
>> same mileage). It's a 97 inline 6 Cherokee. It works, but it doesn't
>> start at first try and it is not very smooth if you want to accelerate
>> from 65 to 75 without a kickdown.
>>
>> "Stephen Cowell" > wrote in message
>> ...
>>
>> "tim bur" > wrote in message
>> ...
>>
>>>depends on the year starting in 04 all pcm,s are shipped with out
>>>software and
>>>it has to progammed by vin
>>>now more salvage yard pcm swapping
>>
>> ^^^^^^^
>>
>> One letter... how it changes things.
>> Tim probably meant 'no'...
>> __
>> Steve
>> .
>>
>>
>>
>>
>>
>>>reigelser wrote:
>>>
>>>
>>>>Hi,
>>>>does anybody know, if there is some programming or calibration to be
>>>>done if
>>>>the engine control unit is replaced? Or do I just plug it in and thats
>>>>it?
>>>>Thanks for the advice.
>>>>
>>>>Jo
>>>
>>
>>
>
> --
> Jerry Bransford
> PP-ASEL N6TAY
> See the Geezer Jeep at
> http://members.cox.net/jerrypb/

"reigelser" > wrote in message =
.. .
> I need the ECU eventually because of a persistent TPS error. My =
mechanic=20
> troubleshooted it and thinks its probably the ECU. But he thinks there =
has=20
> to be some reprogramming to be done, because I tried one from the junk =
yard=20
> before he looked into it and nothing changed (same TPS error, same =
mileage).=20
> It's a 97 inline 6 Cherokee. It works, but it doesn't start at first =
try and=20
> it is not very smooth if you want to accelerate from 65 to 75 without =
a=20
> kickdown.

So it only throws a 24 code? Do you have a manual
or automatic transmission? Any aftermarket parts
on the engine? It's never thrown a 15 (VSS)? That
causes kickdown problems too...

With the TPS, you can actually patch a digital
voltmeter in and watch the voltage as you drive...
won't hurt a thing. If the computer's bad, then
you'd expect the +V to the TPS to fluctuate...
if the TPS is bad, you'd expect the wiper return
voltage to be wrong for the rpm, gear, etc.
That's what I'd do next...
__
Steve
..

It is an automatic transmission. What is the wiper return voltage? The other
voltage I can measure on the TPS besides the ~200mV to ~4V?
I check the message with an OBD Reader. P0123 I think is the number or
P0124, don't remember right now. Are you referring to the Check Engine Light
flashing when you mension a 24 and a 15?

"Stephen Cowell" > wrote in message
. ..

"reigelser" > wrote in message
.. .
> I need the ECU eventually because of a persistent TPS error. My mechanic
> troubleshooted it and thinks its probably the ECU. But he thinks there has
> to be some reprogramming to be done, because I tried one from the junk
> yard
> before he looked into it and nothing changed (same TPS error, same
> mileage).
> It's a 97 inline 6 Cherokee. It works, but it doesn't start at first try
> and
> it is not very smooth if you want to accelerate from 65 to 75 without a
> kickdown.

So it only throws a 24 code? Do you have a manual
or automatic transmission? Any aftermarket parts
on the engine? It's never thrown a 15 (VSS)? That
causes kickdown problems too...

With the TPS, you can actually patch a digital
voltmeter in and watch the voltage as you drive...
won't hurt a thing. If the computer's bad, then
you'd expect the +V to the TPS to fluctuate...
if the TPS is bad, you'd expect the wiper return
voltage to be wrong for the rpm, gear, etc.
That's what I'd do next...
__
Steve
..

reigelser did pass the time by typing:
> I need the ECU eventually because of a persistent TPS error. My mechanic
> troubleshooted it and thinks its probably the ECU. But he thinks there has
> to be some reprogramming to be done, because I tried one from the junk yard
> before he looked into it and nothing changed (same TPS error, same mileage).
> It's a 97 inline 6 Cherokee. It works, but it doesn't start at first try and
> it is not very smooth if you want to accelerate from 65 to 75 without a
> kickdown.

Clean the connectors at both the TPS and the ECU.
And while you have the plugs off, ohm out the sensor
lines as the TPS shares a common ground link with
other sensors and that link can go wonky.

All I have is the 93 schematic so you need the color codes for
your year.

--
DougW