Jso ECU Problem - I think

[Trumpet135]

I have a J30 1993.It has been in and out of the shop for the past 9 months.The car was flooding and then running very rough. I was told that the ECU needed to be replaced. Bought a used one. Worked great for about a week. Then the brand new battery went dead after a few days. Replaced the battery. Same problem.I was told that the ECU was keeping a relay open and that most likely it was a bad ecu again. Does this sound right? I hate to buy a new one from Nissan for $850. Any suggestions?

[yodawill2000]

Who's telling you this ?An Infiniti Tech ?

[Trumpet135]

My local mechanic.Ok the dead battery thing is fixed. It was a relay staying open.The car still runs rough. I said that the ecu is getting wet and causing problems.He also said that this car is known to have huge problems with the computers.

[yodawill2000]

"He also said that this car is known to have huge problems with the computers"

Theres your sign !!!! Totally untrue

The ECU is inside the car behind the passenger side kick panel.How the heck is it getting wet ??

Clean the MAF sensor lately ?New Plugs ??Lots-O-Things can cause a rough idle.

[Elisha]

my ecu kept getting wet too. it was because of the windshield which was not mounted properly when replaced.basically water seeped trough and corroded some pins. on the 1st ecu it took out the pins that controlled cylinder 2 and 6. on the other ecu it took out cylinder 4 and 6.i cleaned off the ECU and re-soldered the pins and it works great now....and it has been 2 years since this happened.

if its the same thing that you're encountering.....see if you can hear higher than normal wind noise coming from around the windshield area.

[yodawill2000]

Interesting.Never have heard of that before.

[Elisha]

here's a pic of what happened to mine:

[ricoh]

Dead battery+leaky sunroof=ECU Problem...to make a short story long.

Maybe my story can help others...I bought a used j30t a few months back and I couldn't believe how fun it was to drive. Powerful purred like kitten and very luxurious. The previous owners did a great job of maintenance and the engine was spotless

. Then, after some very heavy rain, I find that car won't start...It was clicking so iI am thinking Dead Battery? I replaced the battery and (after going through the rough start and white smoke out the tailpipe that I have read about on several other threads)It started.

However, along with the check engine light being on, the car was idling high around 2200 rpm and running very rough? I knew that MECHANICALLY the car was running great (good power, compression, idle, gas mileage, start right up when cold) so it was driving me crazy that now, because of a dead battery, the thing was sputtering and kicking. It was then that I noticed drops of water coming from the sunroof and dripping through the interior roof light mount. After 2 long days of working on the puzzle (and countless incorrect diagnosis from mechanics including a blown head gasket???) here is what I found out.

1. There are 2 small drainage holes in the front corners of the sunroof that can easily become clogged with a small amount of debris.(in my case, it was a small leaf).

2. When the passenger side becomes clogged, the water will not drain out as it is designed to, behind the front wheel well, but will run behind the right side kick panel and will drip directly into the ECU!

3. This problem of design can go completely undetected for quite a while..if it is not a lot of rain, the carpet my not feel wet and no drips will show...also, who checks the floor boards of the passenger side of the car very often?

4. I took my car to the dealer and had the mechanic run tests. He worked on the car for 45 hours and never checked the ECU. Even though the owners manual clearly states that a check engine light is related to the ECU? He called and told me he thought it was "something electrical" and needed more money to keep working on the problem...I asked him if he thought the leaky sunroof could be causing something to short out? He said he would call me back...5 minutes later he called me back and had "magically" located the problem as a corroded ECU filled with water! I asked him if he had ever seen that before and said he said no. Gee, I wonder how he knew that a leak in my sunroof caused my ECU to corrode over and rust over time?

5. The mechanic quoted me $800.00 for the part and $1000.00 in labor. I had only paid $3000 for the car, so I told him to just reconnect the box and went and got my car. It was idling worse than ever, and bucking like a bronco all the way home.

6. I took the ECU out and took it apart. It was corroded and full of moisture. It looked completely useless and had burn areas around the pins. The circuit board was corroded too Just like the one in the picture. I figured what the hell and (using contact cleaner) decided to try cleaning it up...I used a soft toothbrush and some toothpicks and cleaned it up inside and out.

7. Meanwhile, I dried the passenger floorboards which were sopping wet with water, and dried the area around were the ECU mounts. I also, cleaned the debris from the sunroof and blew out the drain with an air compressor.

8. I waited 2 days and then reinstalled the old ECU...the car turned over and purred without me even putting my foot on the gas pedal. I took it around the block and I swear it ran and sounded better than when I bought it.

It is still going strong.

I must say, that this message board and all of the comments I read helped IMMENSELY on leading me down the path to solve this mystery and I want to say thanks.....The Dead Battery, the leaky roof, the corroded ECU full of water....those are all just symptoms of a problem that is easily solved by keeping a small drain hole debris free....I'm off to the beach...and I' not taking the bus...thanks for all of your posts here to everyone and I hope this helps save someone some serious money and aggravation.

[driverdriver]

ricoh, welcome to NICO!!! (it rhymes)

Good first post. Very informative.