Joel SX

Hello, I own a 93 auto coupe (240sx of course) and this is how it goes...

One day I heard of the OBD cable that I could use to scan my car. My car had an idling problem so I thought I would buy it. Bu then I searched and I found out that I could make one for 8 buck in Radio Shack. So i bought the pieces, downloaded the software and of I went. First thing that came to problem was that I could not find the OBD cable no matter how hard I searched. I only found this weird cable, gray in color and 14 pins instead of 12 or 16. My instinct told me this was the diagnostic cable, but I didn't know which cable to put where since the diagrams internet only showed how to connect it to OBD connectors. So I searched and searched and finally I discovered that Nissan had the CONSULT software and was not compatible with pc communications since it actually needs a separate board and an interface and all. I was pissed since now I had wasted money and I really wanted to scan my car and see it on the pc, all the revs and oil pressure etc.

So I looked at the cables and tested each, found the ground and some others that gave me current when the car was on. So I decided to try the cable anyways. I plugged some cables here and there, shorted some in order to try to get the codes out like the instructions in the website said etc. I tried but nothing ever happened. So I left the project and close the car, went about my business.

Next day I went to drive the car, and the transmission would not shift out of park. I used the little red **** and got it to D, but it only took 2nd gear, weird. My first instinct was that it was low on oil since it leaks it and it hesitated when it ran low or took a long time to shift. So poured a whole liter and a half until I topped it, but no effect. Then I tried to scan it again, this time I figured out the part about the light in the back of the ECU. I tried it, and it said "54": A/T control unit circuit. So I thought it was the speed sensor that I cut to get no speed limit cutout. I soldered back, but nothing. In my search for answers I looked it up on the internet and found a couple of things like "limp mode" "clutch worn" solenoid" etc that could be wrong. My instinct told me that I had messed something up when I messed with the OBD cable.

So my first thought was that when I did that, something got short and burned the Transmission Control Unit (TCU). I went to the junk yard and got one out of a 91 model. I plugged back in and no difference. then I thought "When I connected it, it must have burned the part that communicates from the ECU to the TCU, thus the ECU believes that there's a short when there isn't, thus the ECU must be burned and confused. So I went to the Junkyard and bough the ECU from the 91 model. I was exited this day since I was going to be able to drive normally since the last 2 1/2 months of 2nd gear driving. I put it in, turn the car on....... and nothing happened. I was in flames. At this moment the thing I hated the most in the world was A/T... after Hondas that is.. .

So I kept on troubleshooting the thing. I didn't gave up the fight. I tried turning the computer into diagnostic mode, but nothing happened, it didn’t respond to anything. I went online and bought the repair manual on PDF on E-bay, but this would take like a week to get here. So I found this website called "Alldata do it yourself" (www.alldatadiy.com") they provide the whole engine and car diagnostic, repair and specification charts and manuals for all models and all years. I saw the demo and was convinced. I bought the subscription and looked up my problem. Within 2 minutes I had all car wiring diagrams, connector locations, and the diagnostic and problem solving solution specifically for that trouble code.

I printed the diagnostics and diagrams, and proceeded to check all the connections between the ECU and TCU like it said on the guide. I had to disable the freaking air conditioning unit to get to the parts and it was the most uncomfortable thing I had to do in my car, lying back down in the seat with my head underneath the glove box. When I finished this, none of the cables mentioned had a problem. all connections where fine and in perfect condition. AHHAHH!!!! I screamed, the I kicked the glove box and broke it: angry: . The I though it was the "inhibitor switch" since it tells the computer where it is and how to shift gears. I took it out ( remember I said my trans leaks... well this a really funny mess.... well, not that funny). I took it out after 1.3 hours and started to clean it and check it. No problems here. Then I checked the vacuum, good. vacuum valve, good, all sensors good. Pissed at transmission boot kick test, good. no improvement came from all the test.

So another 1.2 hours and 1 whole bottle of Fast Orange later I put the dam inhibitor switch back on and no difference. I said "I'll take it to the friking Nissan dealer. They must have the consult computer and they'll charge me like 30 bucks, but at least I'll know. Then I looked at the diagrams and thought "maybe I did something wrong... maybe I skipped something" But I remembered checking the computer, trying the TCU scan mode, oil fill and flush, test after test. everything. But then I thought "What if I didn’t do it right?" I looked at the diagrams and almost all the circuits used the same 10 amp fuse in the same corner. I *REMEMBER* checking the fuse box, but then, when did I checked it? 2 3/4 months ago? did I checked all of them or was I interrupted while doing it? did I checked them right? did I broke the fuse while putting it in ( they are more fragile that you think)? Is my memory of checking the fuse box another one from checking it some other previous time, like for the radio installation or rear lights or something else that I had checked tem before for?

I decided to check the fuse box again. The first fuse I take out is burned, go figure. and it was the one in many of the Transmission circuits. Now before you go laughing, I remember checking it, but maybe I didn’t check that one, or check it wrong, like in low light. So I replaced it and I turned on the ignition the car, OD light goes on, I turn on the car and it locks out of park, and as soon as I put it on drive and accelerate, I can feel the force of 1st and it shifted. YEAH!!! whoooohooooo!!!! who's your daddy!!!

I replaced the old computers and these worked fine. It seems that the OBD homemade cable somehow shorted the circuit, thus blowing the fuse. the cable was made the right way since I now use it to scan my dad's 2004 Ford Explorer, but it wasn't compatible with CONSULT. So after almost 3 months of trouble and patience and oily messes and slow driving, more than 200$ in travel, parts, subscriptions and manuals and time I learned a couple of things:

1) do lots of research before messing with something you don't know much
2) The easy way ends up being harder to do.
3) Do not mess with a car that you need and daily drive if you are not sure you can do a significant and correct job.
4) make sure you do all steps correctly when working on a car
5) When it seems there's no hope, there might be some left that you can't see.
6) Knowledge is power. The more you know, the more you can do. You can use knowledge now to do the job, and for future jobs.
7) When you do everything and it doesn't seems to work, try it again before doing other things, maybe it wasn't done right.
8) Start with the basics, and then go into complicated
9) Do not change parts if you are not 98% sure they are not working.
10) If you are working in a car and have Hot Pockets sitting around for eating, cover them. if flies sit on them and you eat them, they get you sick.
10) Ignore everyone who tries to put you down. People who say you can't do it say it because they can't. I'll get you frustrated and you'll eventually believe that you can't do it. I had about more than 120 people say "why do you bother so much on a busted 12yr old car, buy a new one".

I hope that this thread helps you in the future and that you understand the basics of why I went trough all this trouble and sharing it with you. Now as a "side effect" from this whole ordeal I have become a self trough "professional" in 1991-93 wiring diagrams and such. I also have the subscription form the website and many troubleshooting guides and manuals, as well as the whole FSM repair manual, specifications, diagrams, adjustments and common maintenance procedures from 1991-93 240's. I'll be glad to help others with their problems but be aware that I log to club240 about 1once a week, maybe more but no promised. So if you have any questions regarding technical knowledge on the vehicles let me know and I’ll try to respond you as soon as I have time. Do not ask for the Alldatadiy.com password and username so you can log on, you want it, pay for it. Hope to hear from ya guys, bye!

yes yes, many typos....

Cape 240

12) When you do something wrong, don't beat the **** out of your car and kick it. You'll end up having to pay for it.


... glad you got it working, its always the last thing you check (lol, the last thing, get it?)

Catharsis

clif notes?

Bryan

Cliff notes:

- Idle problem
- Homemade OBD scanner
- Car no start
- Spend mucho money buying parts and such
- In the end it was a fuse