ECU/cluster swap question

Noneed2Hate

Active Member
Okay so as you guys know, I just recently had a manual swap done to my previously automatic LS.

Issue I have at hand currently is that it still has the automatic gauge cluster and ECU. The car runs okay, but I'd imagine it would run smoother with a proper ECU and without the CEL and ABS lights glaring at me.

Now onto the question at hand.

I should be able to just swap the ECU and keep the cluster with no problems correct? The only difference between the manual and automatic clusters is the P, N, D, 2, 1, R lights I imagine so those just wouldn't work.

Both of the ECUs I have are OBD II, and the manual one I have is a p75 from an 2000 LS.

I do not have a manual cluster.

Just want to confirm before I start undoing stuff beyond my understanding.
 

Noneed2Hate

Active Member
I'm read up on it a bit, apparently I may need a new wire harness or something even though both ECUs are OBDII?
 


Muckman

Not a M0derator
There are differences between OBD2a and OBD2b. Namely the tach is driven by the ecu in obd2b and driven by the distributor in obd2a.

Regarding your original question - I think it would work assuming everything else is the same OBD level.
 

Noneed2Hate

Active Member
There are differences between OBD2a and OBD2b. Namely the tach is driven by the ecu in obd2b and driven by the distributor in obd2a.

Regarding your original question - I think it would work assuming everything else is the same OBD level.
Alright good to know, thank you!

worst case if it doesn't work, I can just pop my old ECU back in.
 

Noneed2Hate

Active Member
Okay, so I tried it out, and no dice. The car would not turn over or even catch in the least bit. I tried resetting the ECU while it was plugged in by removing the ECU and Backup fuses for 10 minutes as shown in this video: https://www.youtube.com/watch?v=41Ev5OkPK4Q

I just popped the Auto ECU back in which is working in the mean time

the A55 is the auto and the A05 is the manual.

Now I think the issue might be connected (or in this case disconnected lol) with the fact there is a slot with no pins in it on the manual ECU, also the connector will not fit that slot properly.


Both are OBDII

I may or may not try to "convert" the auto ECU by desoldering specific transistors (I believe R18/R17 with a bridge put in place on R18), but I don't want to f*** with my only working ECU... :(

a few pics below:





EDIT: apparently the p75-a05 from 00-01 have immobilizers equipped.....
 


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Noneed2Hate

Active Member
Alright, I ended up just removing the immobilizer chip and now the car works, took it for a short 10 minute drive to double check. So far so good.

Currently resetting the ECU so I can let it idle and adjust properly from a clean slate more or less.

The only issue I can think of is it takes a bit to actually turn over. like 4-5 churns (for lack of a better turn) whereas for my auto ecu, it was almost instantaneous. I'm going to assume this is due to the ECU just learning the system it is now attached to
 
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Muckman

Not a M0derator
Try priming the pump by letting the key sit on ignition for a second or two before you start it.
 
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