So I'm a newbie and I'm searching for an EVAP leak that I failed my registration for. Tested my purge valve and sure enough the solenoid reads 25Ohms which is below threshold and it drops vacuum so I'm guessing I need to replace it. I then move onto my tranny switch for the taillights. I plug a paper clip into the harness and an aligator clip from there to my positive on my multimeter so I can test it (since the leads that come with it) don't extend that far deep. It reads 12V's.

I go to turn on the car and none of my ECU lights are showing up. I try to drive it and the accelerator is erratic, I have to instantly curb it otherwise I risk an accident. I'm sure I shorted something. Did I fry my ECU or is there something I should be checking first?


Car actually turns on but this is what it looks like (no tachometer even when revved, accelerator gauge doesn't read anything, fuel gauge says empty even though it's completly full.):

 

It's an 02 SE six speed manual if that helps anybody.

 

What you say you did would not cause any harm. But I think you didn't do what you thought you were doing.

What might have happened is that the paper clip/alligator clip may have touched something and blown a fuse. There are 3 fuses that supply power to the instrument cluster, # 1, # 12 and # 30. These 3 fuses are all in the dashboard fuse panel.
fuse # 1 - top row, first one on the left.
fuse # 12 - middle row, first one on the left.
fuse # 30 - bottom row, second one from the right end. I bet this is the one.

However, when I read your statement of "I then move onto my tranny switch for the taillights", I have no ideal what you are trying to say/do.

 

Your right, it must have shorted something because I saw sparks. The weird thing is when the ignition is turned to the on position I don't see any lights on the dash like the check engine or seat belt, etc. Hence why I thought it was the Ecu.

And sorry for the confusion, I meant reverse lights on the tranny. There is a blue switch five inches from the engine mounts on the driver side that I tested to see if it was getting the right voltage and continuity because my reverse lights don't work. But it works normally so I'm thinking it's a socket, bulbs look fine. Filaments are still connected.

 

You were right it was fuse #30. Was worried it would be more costly. Still trying to figure out my reverse lights. The harness tests at 12V, the bulbs are good. Still gotta try the socket. The switch itself indicates continuity with my multimeter when in reverse. Don't know what else to try.

 

On the reverse lights, check that you have 12 volts in the light bulb socket, which would rule out a wire problem from the reverse switch. Also check that the light bulb socket has a good ground connection - do a continuity check.

There have been people that had the back up light assembly corrode and rust out.

 

I'm not getting 12V's on either socket, I'm getting something like 0.1V. I'm going to buy a light probe to verify. Continuity passes on the right one, no continuity on the left - I'll check ground. I'm not too good with reading wiring diagrams - does the backup light wire assembly run through the interior or below where the exhaust lines run?

 

From the transmission, the wire comes into the passenger compartment on the driver's side. It goes down to the floor and runs to the rear of the car along the doors and goes into the trunk. If you remove the rear seat cushion, you will see the wire harness.

When it gets into the trunk, there is a connector for another wire harness that is the one that goes to the tail/stop/backup/side marker lamps.

There are 2 ground wires that are in the middle of the back piece of the car body, below the trunk latch. You might have to take the plastic trim panels off to get to them, I can't remember exactly.

 

I retested the tranny switch it reads continuous on the connector. I wasn't able to test the actual power on the harness. My multimeter wouldn't fit and I didn't want to try with a paperclip again and risk a short again.

The harnesses all look good and don't seem to be shorting on anything. Retested the socket and it reads 12.4V. Ground looks good as well.





Don't know if this belongs to something else because it terminates from the tranny as well:

 

After looking at your photos, I'm wondering if you are checking the correct switch. There are 2 switches on the transmission, a park/neutral position switch (I know you said 6 speed, but that's what Nissan calls it) and the backup lamp switch.

The park/neutral switch points towards the rear of the car and the backup lamp switch points up towards the sky. The color of the wires on the backup lamp switch are solid orange (has 12 volts on it all the time) and green with white stripe (goes to backup lights.

 

I'm a little confused as I've gotten mixed messages on this. Is the switch bolted to the bottom near where the drain/fill plug is for the tranny or is located on the top? The FSM has it located on the left hand side on the top. What color is the connector or harness? The replacement switches I've seen online all have a blue connector.

 

Wow...nice work Dennis. And Hikaru.

Any changes today?

 

use caulk for evap leak, will take care of code, no need for stupid parts.

 

If you go to page 10 of the service manual, MT section (Manual Transmission) and look at the bottom left of the page, there is a drawing of the 2 switches. It shows the backup lamp switch as being on the top of the trans.

Link to fsm - http://boredmder.com/FSMs/Nissan/Maxima/2002/MT.pdf

Hope this helps.

 

@Prophecy: I think it's the solenoid going bad, I'll have to retest it with a 9V battery but last time I didn't hear a click no matter how many times I connected and reconnected it. I don't think it's closing and opening properly which means the only choice I have is to replace it. I'm getting it on a lift this weekend and I'm going to test the vapor pressure sensor and canister sensors for proper voltage and vaccum as well.

@Dennis: Thanks man so my picture above is correct. It's a blue connector - see the replacement part here: Parts Geek Switch and that reads continous. I verified that's the right one because it has an orange constant voltage wire and a green/white wire for the actual reverse lights on the harness. Still no go :/ This is getting frustating! I don't know where the short/faulty ground is but all the parts look good!

 

If the switch is testing good, then start checking the wires. As I said earlier, the wire harness can be seen when you remove the rear seat bottom cushion. Check it carefully for any damage like a cut.

Go in the trunk and trace the tail light wire harness back to where it connects to the one that goes under the rear seat into the trunk. Put the car in reverse and check for 12 volts on the green/white stripe wire in the connector (white plastic, 10 wire).

 

Good thing it's not an ECU! in the 2001 model it's listed as just about $935.
You could get a used one or aftermarket but either way it cost a lot of money. You'd be lucky to find a good salvaged ECU for 1/2 the cost... Right?

I'm in the market for an ECU just as a back up in case mine blows again. They say some aftermarket ECUs may not work with Certain diagnostic software.

 

1/10 the cost

 

Everything tests good on all of the harnesses including the ones under the seats. Just going to reorder a socket and rewire it myself to a momentary switch, ghetto but I have no idea where a short may be happening.

Clutch went out on Thursday so trying to find a place to let me rent their left as it's easier to remove the axles and all that jazz.