s light blinks after i changed the tcu

[detok]

ok so before my s light would come on solid and my car would go into "limp mode" after doing some searching on here i tried to pull the codes from the tcu but i couldnt find the plug i looked for 2 hrs and i read on here that most of the time its the tcu that went back i have a 90 accord dx and i got the tcu from a 91 accord ex the car shifts fine and feels alot stronger with this tcu but my s light is blinking now is this normal ?

[deevergote]

If the light is on, it means there's an error code. There is a plug, a blue plug, under your dash on the passenger side. If you read the "sticky" thread at the top of this section, you'll even find pictures of the location of it.

The light is still on because it's not a bad TCU. It's a GOOD TCU that is telling you that something else is broken.

[detok]

i lookied took out my glove box and looked for 2 hrs and couldnt find nothing would it be possible that the dx model doesnt have it? my 93 ex has it in plain sight but my 90 dx doesnt?

[deevergote]

There's no need to take out your glove box. It's lower than that, to the right.

Does your ECU have an LED on it? If so, it may be an early model, and MIGHT not have that plug... I have yet to confirm that. If that's the case, I'm not sure how to read a TCU code, unless the TCU has an LED too.

[Joshy]

There's no need to take out your glove box. It's lower than that, to the right.

Does your ECU have an LED on it? If so, it may be an early model, and MIGHT not have that plug... I have yet to confirm that. If that's the case, I'm not sure how to read a TCU code, unless the TCU has an LED too.

It'll still have the plug, even if the ECU and TCU have spot lenses. The lenses are only found on 1990s (and possibly on EARLY 1991s). The codes will flash without jumping the diagnostic plug.

Look behind the passenger side front cowl trim, or behind the carpet in the corner behind the trim. See the cluster of wires in the photo? It should be near those.



Either way, the trim can be removed to pull more slack in the cable.

[deevergote]

They're only on 90s... and only early model 90s, becuase I know a few that don't have them.

[Joshy]

They're only on 90s... and only early model 90s, becuase I know a few that don't have them.

Ah. I figured it was a 90 91 thing. I can confirm that the 90s with lenses DO have the diagnostic plug, because my 1990 has both.

I bet an LED could be soldered onto all the ECU and TCU boards to activate the spot lens feature.

[detok]

i had the tcu with the spot lens and when i turned the key it was one long flash but the new one i put in doesnt have the spot lens but ill look for the plug tomorrow hopefully i find it

[deevergote]

If the TCU has the spot lens, then that's where you're going to see your codes, I believe. Reinstall that TCU, as there is probably nothing wrong with it. See what the codes are by counting the flashes of that light, and fix those problems. If it still works poorly after you know you fixed those things, THEN try the new ECU.

[dano28]

Yep...my 88 Prelude (auto) has the LED's built into the cases. You don't need to jumper a plug to read codes. There is a service plug under the hood that when you jumper it, you can read the ECU codes through the Check engine light, but it's main purpose is for using a timing light to set ignition timing.

[deevergote]

Yep...my 88 Prelude (auto) has the LED's built into the cases. You don't need to jumper a plug to read codes. There is a service plug under the hood that when you jumper it, you can read the ECU codes through the Check engine light, but it's main purpose is for using a timing light to set ignition timing.

That plug you mention in the Prelude is the same plug that is found under the dash in the Accord. The one pictured above.