2G No power to the ecu, but power to other things! WTF!

[95burgundyesi]

I switched battaries out this morning after driving the car. Put the new one in and I turn the key to the on position and no beeping, or CEL. So I instantly knew there was no power at the ecu. Car turns over and the head lights work, along with the wippers. The engine temp and oil pressure gauges all work still.

The car is not getting spark, radio will not come on, or the power locks. I checked the fuse box and used a light tester, everything checked out. The terminals and wires were replaced, still nothing. The was just running!

Is there a relay in the dash somewhere that I should check?Or did I fry something? I am stumped.

 

[knochgoon24]

Do you have all 3 cables connected to the pos terminal? Have you checked your fuses yet?

 

[stevo911]

Pull ECU look for damage and check harness with multimeter.

 

[rush2252]

95 awD TsI?? does yours have the factory anti theft feature? most have the remote keyless entry? If so removing the battery will send it into crank no start of ( theft lockout mode ) Check the Fusible links (large clear top fuses) in your fuse box under the hood. Theres several make sure they arent blown.

 

[95burgundyesi]

I have checka ll the fuses, linkable fuses and they are all okay. I checked them with a light tester and every single one lit up. All the terminals and wires running to it are clean and now new. All are grounded right and sending current to the fuse box.

I have the factory alarm, I am not sure abouta shut out mode. I notice when I put the key into the on position the CEL light does not appear. Showing no power to the ecu. Also the windows, locks and radio do not come on or function, but at the fuse box have current. How can I check to see if it is in shut out mode. The car is not sparking based on me looking for it arcing in the wells when I crank it over.

Tomorrow when I go back to the car I will plug in my stock ecu to see if I get a CEL and or power to the ecu.

 

[infinite_kaos]

I just went through this same problem, though all of my fuses were good, and they werent.

the fusible link for the "motor" in the engine compartment was bad, even though it didnt look bad.

also check wires that have been cut into by anything in the engine compartment, especially the battery tray.

 

[95burgundyesi]

The 20a fuse, that sends power to the ecu. I am going to use my shop manual and test out the distribution system tomorrow. I hope I find it quickly.

 

[rush2252]

i cant find how to reset it but if your car has an audible alarm adn a security light on the dash then you have the anti theft. Anytime you remove the battery your supposed to hook up a 12v source to maintain memory to prevent it from going into lockout mode. I know on NISSANs you stick the key in the door and turn it lock unlock unlock and this resets it. Try sticking your key in the drivers side door and locking then unlock the doors. IF none of the power windows door locks etc are working triple check the main fuse outside. when you test lighted them did you check both sides? one side should light up regardless this is the feed side both light up if the fusible link is good. I think the one your after says battery b+

 

[95burgundyesi]

Yeah I don't have a light in the dash just a alarm. But my locks do not work so I think it is elsewhere. I am going to check things further into the fuse box and have to trace things down the wiring harness.

 

[91DSMdragin]

since you are pulling the ecu and checking it out anyway- while you are there, check the wiring harness coming into the ecu. there will be a wire by itself that takes a detour before it bundles into the wiring harness. that is going to be for the power bypass on the alarm system. its the main power wire coming into the ecu. i believe it is a black wire with a blue stripe(could be wrong about that though) this is going to look like an after market part(since factory didnt actualy instal them,dealers did. i just took mine out all together and put it back to factory standard. hope you get it running.

 

[steve]

Ah Joe, didn't we solve this?

Wasn't the root cause here a blown/bad Alternator fuse?

 

[rush2252]

Ah the dreaded blown fusible link. I remember paying $37 for one on an older NISSAN. It didnt even appear to be broken. After installing a new alternator this was the only thing left. Glad you got it fixed

Kolby

 

[95burgundyesi]

Yes, blown alternator fuse fixed the windows and locks, ect. Ecu was zapped and repaired by Steve.