BCinDC

I recently had the Check Engine Light come on in my 96 ls400, with P1600 code (lack of power to ECU memory). The capacitors had never been changed, so I hoped that was the problem (per the shop manual, I check power to Pin 14 on the E11 connector IIRC, and it was good, which leads to a diagnosis of "Repair/Replace ECU...).

So, I replaced the capacitors with the recommended components [here: https://www.clublexus.com/forums/ls4...capacitor.html ...H/T Cowboy and Yamae ] BUT, unfortunately, that did not solve the problem. I still get P1600, which can't be reset. I assume that the board or some other component died as well, though only one capacitor was leaking and only very slightly.

I have decided to buy another ECU, replace its capacitors and install it. However, some sellers have mentioned the need to "reprogram" replacement ECUs (I intend to buy one with the same P/N, FWIW). I'm not sure if this applies to 96 and earlier, since they don't have a electronically coded key, but after much, much searching I couldn't find a clear answer.

So, when does a replacement ECU need to be reprogrammed by the dealer? And, aside from getting an ECU with the same part number, is there anything else I need to consider?

Thanks,
Bob

timmy0tool

iTrader: (7)

i am not aware of any reprogram necessary on our ECUs. you are right there is no immobilizer built in to them like newer ECUs. i see every now and then folks just getting another ECU, even from the junkyard, and installing with no problems.

absolutely make sure you have the exact same ECU you are replacing. 95-97 cars should all have the same one. some sellers don't know that a 98 ECU is not the same as a 97, though of course the part number should be different.

PureDrifter

iTrader: (10)

only '95-96 are interchangeable. No reprogramming required as there is no immobilizer system in those years tied to the keys.

'97 LS400s (in the US at least) had engine immobilizers which need to be programmed to the keys.

NYKnick101

I think the immobilizer was implemented in 99-2000

Yamae

Nope.
PD is correct.

BCinDC

Thanks for the info. That will make things pretty straight forward. I have another '96 that I was planning to temporarily "steal" the ECU from just to be sure and I didn't want to create a new problem.

Bob