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Auto Trans Problem - Erratic Speedometer Reading & Gear Switching


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#1
goBetong

Posted 24 January 2009 - 08:06 AM

goBetong

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CNY greetings to all,

Most appreciate for any can help to diagnose this problem.

Car : Honda Accord SM4, 1992, Auto Transmission (Local, Kah Motor)

Lately, the speedometer reading and auto trans are both behaving in an erratic manner. At below 40 kph, both behaving perfectly with the gear change as appropriate when accelerating from 0 to cruising at lower than 40 kph. But when speed increase above 40 kph, the speedometer reading will go wild, swinging to beyond 120 kph even when the speed of the car is only about 60 kph. At the same time, my auto trans will start misbehaving - I suspect that it couldn't figure out which gear it should be in.

I suspect that there must be a sensor somewhere which feedback to auto-trans/speedometer and that probably is now malfunction. My mechanic could find it.

Bros - can advise where is this sensor or if my deduction is wrong, please share your experience, Thanks

goBetong

#2
alldisc

Posted 24 January 2009 - 12:23 PM

alldisc

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for such an old car, i can only suspect 3 main culprits.

1. valve body. often ignored, get it removed. serviced and cleaned. then blow with air pistol all the clogs inside.

2. clutch plate - this is of multiple wet type, just like in a kapchai. if worn out, need to be replaced.

3. ECU - for cars with electronic controlled overdrive (unlike the 3 speed saga/iswara/kancil), the ECU plays a vital function in overall transmission function.

other than that, use the proper ATF specified by the manufacturer and make sure the gearbox internals are clean
inside.

once u have done the basics, then only can look at the speed sensors and such. this job is not for conventional mechanics.

#3
vr2turbo

Posted 25 January 2009 - 12:27 PM

vr2turbo

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QUOTE (goBetong @ Jan 24 2009, 09:06 AM) <{POST_SNAPBACK}>
CNY greetings to all,

Most appreciate for any can help to diagnose this problem.

Car : Honda Accord SM4, 1992, Auto Transmission (Local, Kah Motor)

Lately, the speedometer reading and auto trans are both behaving in an erratic manner. At below 40 kph, both behaving perfectly with the gear change as appropriate when accelerating from 0 to cruising at lower than 40 kph. But when speed increase above 40 kph, the speedometer reading will go wild, swinging to beyond 120 kph even when the speed of the car is only about 60 kph. At the same time, my auto trans will start misbehaving - I suspect that it couldn't figure out which gear it should be in.

I suspect that there must be a sensor somewhere which feedback to auto-trans/speedometer and that probably is now malfunction. My mechanic could find it.

Bros - can advise where is this sensor or if my deduction is wrong, please share your experience, Thanks

Is your speedo cable driven? If so, then could be meter problem.

Auto Gear problems can be plenty, from fluid problem, to clutch plate and others.
Not sure whether your auto is driven by TCU (Transmission control Unit) as in my old Auto Mitsu. Could be that also..... sad.gif

#4
goBetong

Posted 08 February 2009 - 07:32 AM

goBetong

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Bros',

Would wish to share this info with fellow petrol heads who may encounter the same problem.

I changed the Speed Speed ($200.00) and the car now runs like a dream. It's just a two nuts and screw driver job, but you will have to take out the intake manifold/others to access it. The main difficulty was finding where it is located (back of auto-trans, engine closer to the firewall).

Solenoid Valves

Since my car is aged (> 250,000 km), I suspect the two Solenoid Valves on the auto-trans need to be changed too. But how to you tell or test whether they are working or not working fine?

Bros' would appreciate any pointers here. Thanks


goBetong