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Transmission Problems with my 93 Honda Accord

August 14th, 2010 · 5 Comments

Some time ago I began noticing some erratic behavior with my 93 Honda Accord transmission.  The problem turned out to be related to the transmission computer and I was able to fix it myself for only a few dollars.

Transmission Control Unit Problem Symptoms

When I started noticing the problems with my Accord, the symptoms would appear for a short while and then disappear.  Some of the symptoms I observed were:

  • The lights on the shift indicator would flash, not show the correct gears, or light up both reverse and drive at the same time.
  • The car would get stuck in what I suppose is third gear, meaning that it would take off very slowly.
  • The car would not shift out of first gear.

Sometimes I would attempt to restart the car at times to make them disappear – this was not reliable.  I began to use my Honda Accord repair manual and http://www.techautorepairs.com/transmission.html to attempt to troubleshoot the problem, testing things such as the shift control positioning,  throttle control cable, map system, electrical components etc and the shift control solenoids and getting the cars diagnostic codes.  I did a tuneup based on the premise that if the car was running poorly it could be sending bad data to the ECU and TCU and causing the problems I was experiencing.  After doing the tuneup I was also a able to drive for a week without any symptoms, leading me to believe the problem was solved – but this was not the case, the problems soon returned. I feared the transmission was going out and I would have a big repair bill or that this would be it for my Honda and I would have to get a new car – however, the fact that occasionally the car would run fine made me feel that this was an electrical issue somewhere and the transmission was still good.

I decided it was time to look into the Transmission Control Unit (TCU) to determine if this was the issue. the article at techautorepairs.com indicates that it is common to find a burned resistor and capacitor in these TCUs.  To do this job I needed the following tools:

I didn’t have any deep sockets, all of my short sockets would not fit, so I had to purchase a set.  I pulled back the carpet and began to remove the TCU with using my new sockets.  Getting the connectors out and removing the TCU took a little work, but I eventually figured it out.  Once out I took the TCU inside and did the rest of the job indoors.

I removed the cover from the TCU with the screwdriver and located the faulty resistor and capacitor. The problem was pretty obvious at this point because the resistor was burned and the capacitor had leaked – this is the exact issue that was listed as a common problem on the techautorepairs.com website.

Faulty Components on TCU

Faulty Components on TCU

 

I took a trip down to radio shack and picked up the needed components, they didn’t have the same capacitor, so I just got the closest one -  The original capacitor was a 220 uf  35v rated at 105 degrees Celsius, the replacement has a temperature rating of 85 degrees Celsius.   I got 15 Ohm half watt resistors being uncertain if the originals were 1/4 watt or 1/2 watt.   I installed the components and reinstalled the TCU.  I ended up replacing two resistors but the second was unnecesary - it tested OK once I had it out of the TCU.  I drove for a few weeks with the carpet pulled back so I could monitor it for heat issues since the capacitor has a lower rating – I did not observe and heat problems and covered it back up.   I have been driving the car for several months now since this fix and have not had any transmission problems since.

TCU with replaced components

TCU with replaced components

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Tags: 93 Honda Accord · Auto Maintenance · Maintenance

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5 responses so far ↓

  • 1 tom // Sep 15, 2011 at 7:47 am

    I also had same problems and found the same burnt resistor and leaky cap got parts wholsale came to 1.96 had same error once reassembled left key on in disgust for about 1 minit while i thought what to do next , light went out then lite would only go on for a few seconds at startup untill about the 4th or 5th time lite has been out all day after that will repost if problem comes back !I guess the computer had to restart a couple of times before error message was cleared probably un hooking the battery would have fixed it quicker Its nice to have all the gears again thanks for the post!

  • 2 John Meadows // Nov 11, 2011 at 10:26 pm

    Thanks for the info. I WILL try it tomorrow. I’ve been “pulling my hair out” trying to isolate the problem !

  • 3 Tom Lunsford // Jun 7, 2012 at 9:02 am

    Had the same problem. Changed the same Cap and resister, discoed battery for a minute and reconnected and the problem was fixed. Drove car for a month and the same components burned out again.

    Any ideas on the electrical that feeds these that could cause the probelm to come back?

  • 4 Administrator // Jul 10, 2012 at 2:05 am

    The techautorepairs site I refer to in the post has additional information and indicates the that three components need to be changed; if you changed only one resistor that could be the cause. I don’t have any further information on the operation of the board.

  • 5 Manuel // Nov 19, 2013 at 5:37 pm

    I have a 93 Honda accord ex, it seems to be the same problem with mine. Found the same culprits, will go to radio shack for parts and there is a guy that works there that does those kinds of jobs in his spare time… will try and then get back to post update.

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