Auto 90 Accord sport light on, tranny not upshifting

[fac90]

Searched but only a few posts about the sport light only on and the tranny starting out in 2nd and not upshifting. It happened on a very cold day. Also, when turning the ignition to accessory position, a noise comes below the indash fuse panel and goes off when applying the brake. I will disconnect the negative battery terminal as a start.

Any ideas?

Also, is driving 45 - 50 mph in the slow lane ok in second gear or stick to side roads?

[accord91lx]

its the tcu... has a fried resistor. replace with another 90-91 tcu.

[fac90]

I will open the TCU and look at the board, but what top speed is safe to drive in second gear?

[accordaffair]

I'd say stay below 45, I mean higher revs will stress the engine a lot.

[accord91lx]

well i'd say drive as fast as you need to... it may shift into 4th gear... if not depending on the health of your engine you could be ok.... i drove my 91 lx manual in second gear once for like 4 miles (from work to home) nearly bouncing the limiter tryin to blow it up and it wouldnt go.......250k and burnt oil like a mofo....... so you should be fine i'd hope

[aleks77]

i had this problem and it was actually my MAIN RELAY, so check into that too

[accord91lx]

i had this problem and it was actually my MAIN RELAY, so check into that too

with the symptoms he discribes, it would not be the main relay, the fuel pump works, and the engine runs.......... which tells me power is not interrupted to the computer(s)......

[fac90]

I removed fuse # 24 (7.4A Radio) to reset the ECU and TCU. No sport light on and no D4 light blinking. Trans runs normal. Unless I look at the TCU board for any burnt parts, it appears it was an electrical problem related to the extreme cold weather.

If it happens again, then its a TCU problem.

At least the TCU "safe mode" put the tranny in second gear rather than first.