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AUTO TO MANUAL ECU QUESTION

BRIANHO13

<- Yum Chocolate
Location
Spring, TX
I currently have a 98 with a manual tranny, my ECU may be fried. From what I have been able to find I should be able to use a auto ecu instead (will be hard to find a manual ecu).

Is this correct?
 
could be... check with these guys

did u verify the the ECM is the root of the no start??... i've been reading thru write ups & looking at wiring diagrams to figure out how to go about wiring push button ignition, since i saw the other thread

i've got a spare 98 ECM... trade ya for relocation brackets?:D
 
I have not verified anything at this point, just anticipating. I have a 99 I can borrow parts from to verify if it is the ecu. But its an auto.
 
i'd assume an auto ECM could be programmed with the appropriate software & swapped into a 5-spd, but that's just an assumption

rockauto lists auto & 5-spd, Fed & CA emissions ECM's separately, with different part#'s
 
Unfortunately these ecu's cannot be reprogrammed. My guess is the auto and manual gear boxes require different ecu's.
 
i would say you need a manual ecu, 98 and later the trans computer is built into the ECU.

you could always just pop it in and see if it works but you might not be able to start it because it will be looking for input from the NSS.
 
a lot of times, if there's transmission sensors or selenoids, the computer needs to see those or else it throws a check engine light. however, in most cases, it does run fine. when i've done auto to manual swaps in other vehicles, i've used the stock ecu and harness from the automatic, and just wire in resistors so that the computer sees a load where the selenoids would have been. hard to do if you don't have the automatic harness though.
 
i would say you need a manual ecu, 98 and later the trans computer is built into the ECU.

you could always just pop it in and see if it works but you might not be able to start it because it will be looking for input from the NSS.
in most cases i've seen (no experience with mopar though), the NSS and clutch safety switch do more or less the same thing, and also use the same pins going to the ecu. but again, mopar might be different.
 
on the later XJs with the trans computer being part of the PCM (on the auto at least) it uses input from the NSS to decide how to control the shift solenoids in the trans, not sure about the input from the clutch switch. This is the reason that you cannot bypass the NSS to start the jeep on a late model XJ like you can on an early model.
 
found a tj manual comp, I would think it would work, anyone else have a thought on it?
 
on the later XJs with the trans computer being part of the PCM (on the auto at least) it uses input from the NSS to decide how to control the shift solenoids in the trans, not sure about the input from the clutch switch. This is the reason that you cannot bypass the NSS to start the jeep on a late model XJ like you can on an early model.

i would say you need a manual ecu, 98 and later the trans computer is built into the ECU.

you could always just pop it in and see if it works but you might not be able to start it because it will be looking for input from the NSS.
The later models still use a separate TCU, and are a separate ECU, not PCM.

I know for sure on my '99s that its a separate TCU under the dash still. I haven't heard anything that they changed it. I was under the impression you could still bypass the NSS on the late models XJs, I thought I had a friend who did it?
 
The only codes that I have seen were ones that come up when people swap from the auto to a manual. The auto PCM doesn't "see" the transmission there, which then throws a code. I didn't have to when I did my auto to manual swap simply because I am OBD 1.

Swap it with your buddy and it should still run fine.
 
SHE LIVES

for anyone who finds this thread in the future, an auto ECU will work in a manual jeep.
 
party1: CONGRATS

funny how things work out sometimes... what you needed was right there in front of you the whole time... c'est la vie!
 
I have a 99 and had a great deal of trouble shooting when I first got the jeep. After chasing wires etc. I figured out that the ECU was toast. I put the computer from a manual in the automatic and it fired up, and its not giving any codes or CEL.
 
Vanimal, I am getting ready to do a auto to manual swap in my '01, you talked about using resistors to show the computer the nss is still there any write ups or tips for doing this?
 
Well, I'm sorry I missed this thread earlier.
The manual and automatic ecus are the exact same hardware inside, it's just the calibration that is different. These ecus can be reflashed if you have the right equipment (which I do). 96-01 ecus can be swapped around in a pinch and run the jeep, 96-98 are Jtec's and can be swapped around through out the years, so you can run a 98 computer on a 96 and so on. The 99-01 are Jtec+'s the 99 ecu only has 1 ignition driver as the motor has a distributor, the later years have 3 coil drivers since in 2000 the motor went DLI. I've taken 2000 ecu's and reflashed them and run them on my 99 with no issues.

All years of the xj had an external Asin Warner TCU which talks to the ecu over CCD, the only Jeep Jtec's that have the internal transmission controller are the ones on the Grand Cherokees and any other Jeep that uses a Chrysler transmission.

What's nice about the Jtec is that you can reflash them and if it has the supporting hardware you can use it to run anything.
 
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