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Service Engine Light doesnt work

Old 02-14-2017, 04:24 PM
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Service Engine Light doesnt work

Hi guys

I recently updated my digi dash bulbs to LED bulbs. It was horrible, if I had known that is is such a pain in the a** to do this, I'd never started with that. Anyway, I managed to do the hard parts like reconnect the monitors with those many pin cards.

My question: My "Service Engine Soon" lamp (also replaced with LED) doesnt work. It also never worked before with a usual lamp. (I own the car half a year and I cant remember lighten up).

Usually it should lighten up at the start, am I right? So is it ok to just give a s*** and use the car? uprgaded some things like hooker headers, new cat etc. no problems, only maybe little bit bad MPG (but I changed O2 sensor, new fuelfilter etc.)

Thanks for your help

Here is my dash with LED:

Old 02-14-2017, 04:54 PM
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Re: Service Engine Light doesnt work

Assuming this is your profile a 88 tpi maybe. You can use a test light with the lead hooked to a hot source and the tip backprobed into connection a5 of the ecm Ben/white wire.
If the light doesn't illuminate koeo than the ecm is more than likely faulty. If it lights than there is a power issue at the bulb location or a open in the Brn/wht wire to the ip.
If the old bulb was burned out the polarity maybe backwards on the led.
If this is your tbi car a5 is the same for the ses ground.

Last edited by Tuned Performance; 02-14-2017 at 04:58 PM.
Old 02-15-2017, 01:12 AM
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Re: Service Engine Light doesnt work

Do you mean I should check the ALDL of the car and the ECM Diactnostic request or what ist "a5 of the ecm Ben/white wire" and where do I find that? I'm sorry I don't really get what you are saying.

I checked the LED bulb and tried other ones and also in both ways. It never lights up.

The car has a hypertech chip on it, could it be that?

And does it really matter? Do I have to be concerned anyways, cause the car is running fine. I mean, older cars don't even have such error codes...


Last edited by Smackdown; 02-15-2017 at 05:06 AM.
Old 02-15-2017, 04:13 PM
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Re: Service Engine Light doesnt work

The pinout I'm referring to is at the ecm
Old 02-17-2017, 01:42 PM
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Re: Service Engine Light doesnt work

Alritght, the power cable from the bulb was cut off by someone. I reconected it and did that paperclip thing with the ALDL, 2 Codes:

Code 12: 12 Diagnostic mode / ECM functioning No reference pulses to ECM.

What does that mean? How do I solve that?

Code 36: MAF (Mass Air Flow) sensor
burn-off circuit failure OR fault in direct ignition system OR Missing
pulses in electronic spark timing signal.

What does that mean? How do I solve that?

These information dont help me...
Old 02-17-2017, 01:56 PM
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Re: Service Engine Light doesnt work

Hi Smack
The code 12 is the normal. It will flash 3 times. If no other codes flash, it fine. 12 will always be your first to flash.

On the code 36, it has to do with the MAF Burnoff. it burns off any debris on the fine wire in the MAF. It could be the relay on the firewall above the brake booster. There will be 3 relays.... a Fuel Pump Relay, a Mass Air Flow Sensor Relay, and a Mass Burnoff Relay. Burnoff may be bad.
GL
Bob
Old 02-17-2017, 01:58 PM
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Re: Service Engine Light doesnt work

Old 02-17-2017, 01:59 PM
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Re: Service Engine Light doesnt work

Code 12 is normal when retrieving codes.
code 12 is for the ecm not receiving a pulse.
thats thrown when retrieving codes engine off.
​​​​​​​


Old 02-18-2017, 12:44 PM
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Re: Service Engine Light doesnt work

Thank you for your help Tuned Performance and Bob88GTA!

I disconnected the relay and also the battery afterwards for 30 seconds just to try if that something helps and voila, after that I checked the error codes again and I had just the error code 12 which is normal as you say

But one more question. I changed the bulbs to LED, also the SES bulb. When I start the ignition, the SES bulb shines bright. Then when I start the engine, the SES bulb shines dim, not as bright as before but it still gives light. But as I said, there is no error code. Do you know why this happens? The SES bulb shouldn't normally light if here is no error code, right? Is that maybe the reason someone cut the wire off that the bulb never shines?

Thank you for your help!
Old 02-18-2017, 02:14 PM
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Re: Service Engine Light doesnt work

The ECM controls the ground side of the bulb. So either the ECM is grounding the wire on the negative side or the wire has a short to ground or there's an issue with the circuit board on the instrument cluster.


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