Automatic '90 Accord transmission shifts 2nd and 4th only...
 

I have a 1990 Honda Accord EX with 250,000+ miles (and the car has been in my family as original owners). Over the summer I put in: new spark plugs, new spark plug cables, adjusted the gap on the valves to factory specifications (and compression is to factory spec.), replaced vacuum hoses and new distributor cap and rotor (from the dealer). The EGR valve is good, didn't need replacing.

So, all seemed well until I drove the car about 50 miles, then it decided to pull a fast one on me. When I start from a standstill (in drive), it is in 2nd gear and won't shift out of 2nd with acceleration. I have to manually shift into 4th at higher speeds (say, 45 and up). Same thing with deceleration, I have to manually shift to 2nd. So, the car won't acknowledge that it has a 1st and 3rd gear, nor will it shift between 2nd and 4th. So, it has been sitting in the driveway since summer.

Any thoughts? Some folks say to flush the tranny fluid (which I haven't done for a few years, my bad). Some say that there is a "pan" underneath that could be dirty and needs to be cleaned (but others say that this theory is bull). I could sure use some good advice, hopefully someone out there has had this problem before and was able to solve it effectively.

it sound like the transmission control unit. Its located on the passegers side under the floor carpet. They have some capacitors that go bad in them. I Ordered a new one for my son's 1991 Accord which was doing the same thing but i also just changed the capacitors out and it has been working for over 2 years now. Problem: The usual problem with the Honda Accord transmission, namely the 90,91, -, - Accord, is a bad transmission computer. What happens is that the transmission computer has a couple cheap parts that fail. The failing parts may or may not automatically put the TCU into a saftey (limp) mode (aka, the "fail safe strategy.") The three known failed components are two resistors and a capacitor inside the transmission computer. The symptoms are of several types. The car "S" light or "D4" is on (stuck on no matter what gear selection) or blinking and the transmission won't shift into any gears or sometimes stuck on a certain gear. The trouble codes could be 1,2,7,8,9,15 or None. Shifter interlock control unit buzzes. When the driver steps on the gas the rpm goes high but the car refuses to move at the expected speed. By resetting the TCU, either by the proper method or by disconnecting the negative battery for 5 to 10 seconds will eliminate the problem, but only temporarily. The resistors R41, R42, R43, are overheated or burned and capacitors C27, C28, C32, C33, C5 leaking or shorted. Some resistors will be burned off and we do not know the values. A common sense approach is to consult a working TCU and read the color code on the resistors or start with the highest resistance and go down. Find the best wattage resistor or the best voltage capacitor that can fit. The problem originates with the electrolytic capacitors leaking. Often, the capacitor short circuits frying other components such as your resistor. Another words, the burned resistor is a result of another component failure, namely the capacitor. The fix is to replace the bad parts. See the values below.

Parts values: R41 is most likely 15 Ohms; R42 is 15 Ohms, both appears to look like a 1/4 to 1/2 Watt; Capacitor C28 105`C 220uF 35V Nichicon H9146

Thanks for the detailed analysis Eaglefixer. That may very well be the problem with my car. The "S" (sport shift) light did come on periodically just before this all happened. And the "check engine" light would come on, but less frequently.

When you say you ordered a new one for your son's car, did you mean you ordered just the capacitors, or did you have to replace the entire ECM? I was checking on the computers online and they are a bit pricey.

Thanks again.....

I would check for error codes stored by the ECU and TCU since the check engine light and sport light turned on.

I think that your 1990 accord has the blue two pin connector that you short and you can count the check engine light flashes for the ECU code and the S light flashes for the TCU code. See: http://www.techautorepairs.com/dtc.html

If not, there is an LED on the TCU and ECU that will flash the code.

I did order a overhauled tcu but ended up just changing the capacitors which cost me about $5 which included shipping

I have an 91 automatic accord. it just recently started doing the following: when i put the car in drive and try to accelerate it doesn't seem to want to go...very sluggish. just wandered if it could be the tcu. the speedometer hasn't worked for several years and the "s" light has always flashed when the speedometer stopped working. maybe it flashes due to transmission problems. i recently had an oil change and the service notes indicated a transmission leak which was new. could a leak cause the hesitant acceleration or is it something more serious. the care has about 180, 000miles on it. fearful the transmission may be going out. thanks

Check for engine and transmission codes. See the link I put in my previous post.

Swamplover: The reason for your speedo problems is that the VSS (vehicle speed sensor) has an intermittent problem and occasionally causes the speedo to show zero speed and will also turn on the "S" light...Very easy to fix...holler if you need help.

Same issue
 

Jackson , I am having this issue with my 1990 Cb7 Accord. What should I do ?

Need same help