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1996 Nissan P/U Engine Control Module

Dealer says smog test “rejected” due to faulty ECM. He’s happy to install one for $689 plus tax plus $400 labor. Provided I could find one, is that a part a weekend mechanic could install?
Veh stats: 1996 P/U, XE, 2.4L, man trans, 165,000 mi, a/c

$80 on ebay, Should be an easy install. Would likely be very inexpensive from a pick and pull type salvage yard in your area


Of course, these ECMs are VIN coded, and may cause a failed emissions if your jurisdiction looks for that. The dealer will flash the ECM with the correct VIN and options for your truck. An eBay ECM will not come like that, but with the program from the previous truck. Buyer Beware!

BTW, is the truck running OK, or is it having drivability problems? It is rare for an ECM to go faulty, and doubly rare to be faulty without any other symptoms. This is the textbook case for a second opinion, especially from an independent mechanic that comes recommended. Check the ‘Mechanix Files’ on the Cartalk home page for a recommended mechanic. The ODB-II port is a powered port, and a blown fuse to it may cause connection problems.

Agree the diagnosis is suspect. I don’t think a 96 model would be VIN encoded, and as long as the engine and transmission are the same I don’t think any reprogramming would be needed. Not sure about other states, but in Texas the VIN is taken off the car, and not read off the ECM.

If you can take the seat out, then you can easily replace the ECU, its under the passenger side of the seat.

However, I smell a rat here. Did the dealer tell you it failed the smog test? Is the dealer doing the smog test? Did you ask the dealer to do the smog test? Did you have a check engine light?

Give us some more details here as to what led you to the dealership for in the first place. It is quite possible that you don’t need a new ECM in the first place. There is a slot in the side of the ECM that is used to pull codes without a code reader. It gives the codes by flashing the CEL the way it did with OBD 1. If the slot is in the wrong position, it will appear like a failed ECM to a code reader.

Thanks for all the feedback. Dealer didn’t do smog test, but two different smog stations (neither with repair capability) did, as did the DMV Emissions Lab (which gave me the revised drive cycle I used in vain). All results “rejected”. I will check all fuses (are there any to check under the hood, or are they just in the box at the bottom left of dash?). Only problem with truck is a recent (a few very hot days) thing where it sometimes runs very rough (after running fine for several miles and then being shut off for several minutes to a couple of hours). Of course that could have been the cheap gas I put in at the next to last fill up.
PS Went to dealership only bcuz State lab said best Nissan tech in state worked there.
PPS Got new battery in December. No ck engine light for probably six months or more. No prior problems passing smog.

Update: checked fuses. all good. now what?

Check the slot on the side of the cpu to be sure it is in the correct position.