I have done a very thorough search of the site and though I find these issues individually, I haven't found anyone with all of these.


I got this car from a friend who had parked it in his yard for roughly 8 years. After fixing several small issues I drove it for about 2 months and had to replace the ECU (figured it out reading stuff here). All of this time I have been dealing with the A/T slipping and erratic shifting issues. When I start the car first thing in the morning and put it into D4 there is about a 3-5 second delay before the car will start to move. While driving it will slip slightly when shifting between 2-3 and 3-4. When I turn the AT will down shift and immediately reshift back up in what feels like it is slipping. I have checked the fluid and it is at an acceptable level and color.


Last Sunday I was going to pick my son up and had another issue. Stopped at a red light and when I took off it did sort of a stutter through 1st,2nd, and 3rd gear pretty quick before settling into 2nd gear and accelerating fine. Got to cruising speed (45mph) and it suddenly downshifted to 2nd gear. I put the shifter into D3 and it shifted normally back into 4th gear. It did this twice over about 2 miles before it would not shift out of 2nd gear unless I put the shifter into D3, but it would stay in 3rd gear.


When I got where I was going I jumped the blue service connector and got the code out of it:
Check Engine Light Code was 31 - A/T B Signal
D4 light Code was 15 - Kick down Switch Shorted?


I pulled the backup fuse and cleared the codes and drove home without a problem other than the slipping issue. When I got home I pulled the codes again. This time I only got CEL Code 41 - Primary O2 sensor Heater.


I cleared the codes again and drove it all week with no issues (besides the slipping issue) until yesterday. Same issue where is would down shift all of a sudden and not upshift unless done manually. Pulled the Codes again:
CEL Code 41
D4 light Code 15.


Could this Kickdown Switch Code be causing my slippage issue as well? How do I fix this problem?


Any help would be greatly appreciated.


If I missed anything please feel free to let me know.

 

Code 15 for trans is mainshaft speed sensor circuit electrical fault. Fault can be sensor, connector, wiring, or TCM.

I will summarize but a shop manual (see Online Manuals post in DiY forum) is better.

Diagnosis is to disconnect electrical connector (near distributor and inside of battery on lower engine), and measure resistance of two sensor side pins. It should be 400-600 ohms. If faulty, replace sensor.

If good, reconnect sensor, and measure resistance again at the TCM by disconnecting the D connector and measuring resistance of pins D19 and D12.

If good (400-600 ohms), the TCM is the problem. If resistance is short or open circuit, find wiring defect between sensor connector and TCM connector.

good luck

 

Sorry for the long delay. Life has been terribly busy.


I changed out the MSS and the car drove perfect for a day. I normally drive to work and then right home. Yesterday I had to run a few errands and take my son to practice. Almost to the school (last stop) the problem reappeared. The only difference is that this time there is no D4 error code. As long as I just drive short trips (under 10 miles) it runs great. Anything over that and it starts to slip when it is running through the gears and randomly dropping into 2nd gear. It is almost like it is dropping into a passing gear.


I had to replace the ECU a couple of months ago because of a blown cap. Could the conditions that caused that ECU cap to blow be causing the same problem with the TCU? I haven't had time to remove the TCU and inspect it. This problem has been manageable because I generally only drive to work and home, but over the last week I have had to take/pickup my son from practice which seems to be when the erratic shifting happens. Seems when the car gets hot it triggers something that makes this happen.


I have downloaded the service manual and will be going through it today to see if I can make heads or tails of it. Any additional help would be greatly appreciated.


Thank you!

 

TCU faults are not frequent but do occur in this generation. I would wait to see if same code reappears. Did you perform any of the checks I described which would isolate the electrical fault?

Suggest you check for TCU code even though light is off. Some codes don't set the D4 flashing.

good luck

 

I started the isolation process with the MSS and it was reading 725 ohms. I stopped there and replaced the MSS. I figured that was my issue and stopped.


The D4 code I was getting originally only showed when I jumped the service connection. No flash while the car was in motion. After the issue reappeared last night I jumped the service connection and the only code I got was the CEL 41 (Main O2 sensor warmer). When this problem originally started I got D4 code 15 (MSS Fault) and CEL 31 (Automatic Transmission Signal B)

 

You can wait to see if perhaps a code will surface to provide some guidance.

However, a replacement TCU is readily available for <$20 on ebay. If your symptoms suggest an electrical problem. For instance does fault appear after engine/trans fully warmed? Does problem appear abruptly or gradually arise?

You will see in the shop manual a section on Symptom-Component Chart, Hydraulic System. This will provide some guidance on possible problems, however many may only be repairable by trans removal/overhaul.

good luck

 

The problem will start when the engine/trans are fully warmed. It starts gradually by first taking high RPM to shift from D3-D4. Then it will kick down from 4th gear to 2nd gear. Usually this can be cleared by manually shifting to D3 then back to D4. Then it will progress to the kick down and only shifting into 3rd when I manually shift the lever to D3 but if I move the lever to D4 is will immediately kick down to 2nd again. At this point I have to drive in D3 to my destination. Usually this happens when I am close to where I am headed since I never drive very far.

 

Problem symptoms suggest a hydraulic fault. Most are not addressable w/o trans removal.

It may be that time car sat up is affecting transmission. Perhaps changing ATF w/ Honda DW1 (3 drain/refill/drive cycles) and continuing to drive may gradually improve performance.

good luck

 

Where is the best place to find DW-1 at a reasonable price? Local dealer wants $8.30/qt. Any solid substitute? Im wondering if this fluid was changed out and something other than DW-1 was used.

 

You can get good prices on ebay, but need to buy a case to get best price. Three successive drain/refill/drive cycles will require about a case.

Many have used Castrol ATF as a substitute and is supposed to be good.

good luck