ecu check, light stays on!?

[zoopsta]

Hey guys,

A while ago (like 6 months - 1 year) i did a diagnostic on my ecu and got an error code 8 (i think it was) - it was to do with TDC.

Anyway, i decided to do another one tonight, however the light STAYS ON during the test. Now you might say nothing is wrong, but WHY does the light come up and stay on while im DRIVING?

Thanks for ya help guys!

[bennjamin]

did you reset your ECU after "testing" ?
Does it randomly come on during driving - or simpyl stays on ?

*ECU MAN help*

[ECU-MAN]

zoopsta, if the check engine light comes on while you are driving and there are no codes in you ecu, chances are its code 0 "internal fault with the ECU". the best thing to do would be what ben said, reset the ecu, then start the car let it run till it warms up ( take it for a normal drive ) turn your engine off, then check your ecu. if the check engine light didnt come on while you where driving there should be no codes.
as soon as you see the check engine light come on again check your ecu, if you get the same thing then your ecu is the culprit. and yes code 8 is TDC, and it should be looged into the ECU fault memory if its still playing up. if it hasnt showed up for a while chances are its ok.

[zoopsta]

hey there

funny thing is, i actually did what you guys suggested (reset ECU) and i started the car with the engine light still on (its on all the time).

But the way i resetted it, i took out the fuse from under the bonnet for the ecu and left it out for ages (longer than 15 mins, i was having dinner) - i put it back in, started the car, the light was on, but i let it warm up as i usually do.

Oh, actually, before i started the car, i diagnosed the ecu, still same thing (constant light on)

would it be the ecu? or should i test the ECU again (after resetting it again) after letting the car warm up and taking it for a small drive?

Btw, i didnt reset the ecu by unplugging the negative from the battery because i dont want to lose my H/U settings :(

[flipmods]

Might sound stupid but did you take the bridge wire out?

[zoopsta]

if you can explain/extend what you're talking about, i might be able to answer :)

[zoopsta]

ok, hmm

i just thought about what you said, and you're referring to the paperclip i stuck in to complete the circuit?

If no paperclip is there: I turn the key to on position, the relevant lights light up and turn off (like SRS, oil, battery etc) and the check engine light comes on and then turns off too (it makes a click noise every time when it turns off)
and after i start the car, the light comes back!

If a paperclip is there: the engine light stays on constant.

[ECU-MAN]

when you checked your ecu for fault codes, did yo take the jumper wire out of the 2 pin connector afterwards, or do you have the flashing LED on the ecu itself

what year car do you have and what car

[zoopsta]

EG 94 civic gli sedan, i think EG8

Can you elaborate ECU-MAN?
I dont really understand ya! :(

I just put in the jumper wire, turned the key to on and the engine light is just staying on.
I turn the key to OFF, then take out the jumper wire, turn the key to on, the engine light comes on but then turns off (like its supposed to) - but comes on again when the car is started.

Is this what you wanted to know? Why would you leave the jumper wire in there after checking for codes?

I dont know if i have a flashing led on the ecu, its stock for all i know?

[wynode]

Once you are done checking for error codes take the 'jumper wire' out and start the car. The MIL will come on for a bit and then go off. That's normal.

[zoopsta]

I dont think u understand lol!!

I DO take the jumper wire out when starting the car, why would i leave it in there :confused:

And after i start the car, the LIGHT STAYS ON

(when i mentioned the light turning off, that is just in the ON position, not starting the car - without the jumper wire inserted)

So a basic summary:

From ecu diagnostic: Light stays on
After starting the car normally: Light is on always while driving

[ECU-MAN]

ok, we where asking if you are removing the short connector to make sure you didnt forget it on as this will make the light stay on.

dont worry acout the LED I mentionedn you have an OBD1 car, it doesnt use the LED on the ECU for codes.


sorry to say but I think your ECU is rooted

[zoopsta]

Yea the LED thing threw me off a little, but thats cool :)

So you think its the ECU eh?

The car's running fine, i dont get it :confused:

What can i do about it? just take it to a mechanic? could they swap and check with another ecu ? would they charge me for that? lol..

Thanks for your help man

[ECU-MAN]

I doubt a mechanic would have a spare ecu laying arount foryour car. but yes that would be the best test. and Id say they would charge you.

[Snoop_gee]

ok the engine symbol appears onli after i driven it around for 10-15mins it doesn't appear on startup. I checked the ECU and found the following
1. Oxygen Sensor "A" (Primary)
7.TP Sensor (Throttle Position)
17.VSS (Vehicle Speed Sensor)

can i fix this or do i need a mechanic to do it? And what are the possible dangers if it is left unattended?

[ECU-MAN]

1 oxyren sensor: will make your engine run rich, use exsessive fuel and be down on power.

7 TP Sensor: could cause the engine to stall at Idle, also cause flatspots on acceleration or under load, high or low idle.

17 VSS: in an auto would cause shift and kick down problems. speedo drop outs,

depending on your mechanicle and technical skills whether you should take it someware to have it fixed. sensors arnt hard to change, but if you dont know what your doing you could be replacing sensors when infact its a wire problem or not setting up sensprs correctly and cause more problems.