# ECU Failure



## wakingmammoth (Sep 10, 2010)

Hello All,

My 1999 QX 3.0 V6 (I'm in the Uk so Maxima to you guys) gave up on me last Friday. It had been fine and then all of a sudden the engine started running rough before giving up altogether.

The RAC guy found that the fuse on the circuit for the ignition coils had blown and when he replaced it the fuse blew again. He suggested that it was an electrical fault somewhere on the circuit which he wouldn't be able to investigate at the side of the road so that car has gone into the garage.

I've had a call today from the garage to say that they suspect it could be an ECU failure. The guy said he couldn't detect any feed coming out of the ECU which is why he suspected it had failed. They would have to send the ECU to have it checked to confirm the failure.

I was wondering if anyone had an opinion on how plausible this sounded as a new ECU is going to cost. I can't find much mention on the forums of ECU failure on Maximas so I'm guessing that this isn't a common fault?


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## 4thGenTinkerer (Nov 1, 2009)

Check your fuses, the reason the ECU isnt giving a signal to the OBDII port is because a fuse is blown. Usually it is the fuse which is on the cig lighter circuit. Dont quote me on that one, just be sure you check them ALL. Once you replace the fuse you can pull the codes. ECU's are usually pretty hardy, I am not an expert but I have seen a few maximas in my time and cant recall an ECU just frying. Usually there is some outside stimulas which makes them go bad. I.E. sombody probing the pins, aftermarket stero improperly installed etc.
Good Luck.


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## wakingmammoth (Sep 10, 2010)

4thGenTinkerer said:


> Check your fuses, the reason the ECU isnt giving a signal to the OBDII port is because a fuse is blown. Usually it is the fuse which is on the cig lighter circuit. Dont quote me on that one, just be sure you check them ALL. Once you replace the fuse you can pull the codes. ECU's are usually pretty hardy, I am not an expert but I have seen a few maximas in my time and cant recall an ECU just frying. Usually there is some outside stimulas which makes them go bad. I.E. sombody probing the pins, aftermarket stero improperly installed etc.
> Good Luck.


Thanks 4thGenTinkerer, the garage have since got back to me to say that the ECU is fine. It was actually one of the igintion coils having melted a wire on the loom that caused a short circuit. Car should be sorted in the next couple of days. Again, many thanks for your help!


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## 4thGenTinkerer (Nov 1, 2009)

Good deal! 
Glad they were able to sort it out. 
No need to thank me, sorry I didnt see your post earlier. 
That makes me want to go check my harness (loom) and replace all my coils! 
Just wondering, is your car a automatic or 5 speed? 
I have an auto and am gathering parts for a 5 speed swap. Its gonna be a PITA but will be worth it in the long (1/4 mi) run. 
Take it easy and best of luck to ya.


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## wakingmammoth (Sep 10, 2010)

4thGenTinkerer said:


> Good deal!
> Glad they were able to sort it out.
> No need to thank me, sorry I didnt see your post earlier.
> That makes me want to go check my harness (loom) and replace all my coils!
> ...


Mine's an automatic. I actually replaced all the coils two years ago after the car started running rough (dodgy coils are a known problem on the 1999 4th gen) so am a bit gutted that one has gone again so soon. 

All the best with your engine swap.

United > Liverpool


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## 4thGenTinkerer (Nov 1, 2009)

Indeed, the coils are a known issue for the 99's. When I did the first engine swap I got six new Hashin(sp?) coils from a parts store. They work great, I have about 13,000 mi. on them and not a single issue. 
I was meaning a trans swap : ) But thanks all the same! 

I need a clutch and a shifter to feel properly connected to my car. LOL. 

Plus a 5 speed actually increases torque to the wheels, an automatic wastes about 15% of available torque when tranlating that force through the trans and to the wheels. 

They are much more fun to drive too! 

5 speed MT Maxima's FTW!


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