The CEL code 15 is for ignition output signal.

The S light is showing a bunch of codes. There is not code 12 in my list (which could indicate a bad TCU). The code 14 indicates a bad ECU.

Before jumping to the ECU or TCU, check your grounds.

There is one important ground that I would unbolt. Then clean the eyelet and bolt with a wire brush so you are sure that you have a good ground.

That ground is on the thermostat housing. It is where the lower radiator hose goes into the engine (NOT the upper hose as labeled in the picture below). See if cleaning that ground helps out.




If you have a U-Pull-It junkyard nearby, you may be able to buy both for pretty cheap. Also check out car-part.com. That site can search for used parts from junkyards that will work with your 91 accord. You can sort by price or distance to see if there are some cheap parts in your area to get an idea of the cost of replacing either or both of these units.

 

I'm sorry PAHonda but what does ECU and TCU mean. Is that something that is worth fixing or replacing. Thankyou for all your help so far. I appreciate it! Remember I did get this car for free but I don't want and can't really afford to put a whole lot of money into it

 

The ECU is the engine computer. The TCU is the transmission computer.

Clean that ground up I mentioned before. That is something you can do for free. You just have to remove a bolt, use a small wire brush to clean up any corrosion, then bolt it back down.

That car-part.com site will pull up prices for used ECUs and TCUs in your area, so you will have an idea of the cost. New ones are very expensive.

 

I will clean that bolt tonight after work but if that doesn't do the trick and I need to replace both of those where are they located. Is that behind the pass. kick panel too?

I notice that some of these computers might be under the carpet on the passenger side. Well the car leaks when it rains and the entire passenger side floor is completely soaked. Might that have something to do with it? This happened last week Friday and it is still soaked. The guy who had it before me said it died in the rain when he was driving it.

 

The ECU and TCU are on the passenger side of the car under the carpet.

If you have a water leak, then you need to find the source of the leak and fix that first. Use a shop vac to remove the water from inside of the car. The ECU and TCU might be getting wet and causing all of these problems.

If the ECU and TCU work when they are dry, then fixing the leak should resolve the problem.

 

Okay I went and checked for those ground wires on the thermostat housing and there is nothing there. I pulled back the carpet and it was still very wet. I'm thinking of taking the ecu and the tcu out so they can airdry. I know where the water is coming from I just need to seal it up. Is there someplace else I can look for those ground wires?

 

I dont have ground wires on that bokt either...

Bluedeamon, I had same issues... I replaced mu ecu, and the tcm with junkyard parts I picked muself.. Cost me aboit 40 bucks, 20 each... however I had to pull almost 15 tcm before I found one that was not damaged. Inside the tcm, in the bottom right corner are two little connectors, sometimes the connectors burn out... One controls first and third gears, and other controls second and fourth.. Its possible they are damaged as u said the floorboard is soaked...

Id pull those computers, let them dry... Open tcm and check those two little connectors... If they dont look burnt, dry it all out.. And put back in...

I also had to take off, open up, and replace half the componets inside my distributor. The ignition control mod, and the other little plastic component in there... these were my issues with running and stalling, my ecu was fine..

Its best if u can go to a junkyard... Tear stuff apart and open... See it all.. Then start replacing these easy, 5 dollar parts... Old car, cant hurt to replace some things that cheap!

 

Well so far the cheapest I can find a tcu is $50. But that doesn't mean that it will work. Is there a way to test these? I took both computers out and brought them inside and I'm going to hook them up tonight just to see if airing them out helped.

 

Test them in car... Plug em up and see if it will let u shift...

Also check the wires on the solenoids.. Under hood on trans is two solenoids... I had to zip tie a wire into yhe grey clip for second gear to work...

But as I said, its best to get into a junkyard and open up the tcm, and check to see if the resistors are burnt(bad), or not burnt (ok/good)... Its only four little screws to open tcu, do it while u got em in the house, phillips driver.. Look at all the little resistors... See if u can find a burnt or black one that looks fried...

 

I never had a problem with shifting in this car it was just when I punched it that there wasn't any response from the throttle. I'll check those resisters out tonight when I get home. Thanks for the help!