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Has any one had success rewiring the check engine light in a cluster that had the bulb removed? I need to rewire mine too pass emissions, and i'd like to try doing this without having to replace the whole cluster. I already tried trying to solder a new bulb in but it didn't work. I'm guessing the contacts in the board are damaged beyond usability.
So far I've dug up the circuit schematics but I'm not sure if I can just wire a bulb to the BRN/WHT wire and then ground the other end of the bulb. From what I can tell, it seems the light is on all the time and the PCM switches it off by disconnecting the ground signal? So does that mean the wire coming from the c230 connector is a ground signal and I just need to have the positive terminal of the LED bulb connected to a hot at all time power feed. Or maybe on at ignition power could work too?
Last edited by Kokomastah; May 8, 2019 at 11:01 PM.
Reason: pictures added
From: Jacksonville, FL (originally from Toronto Canada)
The SES bulb gets power through the GAUGES fuse (pink wire) and grounds in the PCM (brown/white wire). The PCM controls the ground so that it can display the bulb test during startup, remove the ground (turn off the light) during normal operation, and enable the ground (turn on the light) when a fault is detected.
You want power to one side of the bulb (LED actually) from the GAUGES fuse because it's available in run, bulb test, and start conditions. The other side of the bulb goes to the brown/white wire to the PCM to provide ground when required.
When you tried to solder in a replacement that didn't work, did you ensure that you had the LED polarity correct? LEDs only flow current in one direction so if you connect it backwards you'll get no light even if the circuit is working properly. It's unlikely the board contacts are bad unless they have been totally melted during soldering attempts.
The SES bulb gets power through the GAUGES fuse (pink wire) and grounds in the PCM (brown/white wire). The PCM controls the ground so that it can display the bulb test during startup, remove the ground (turn off the light) during normal operation, and enable the ground (turn on the light) when a fault is detected.
You want power to one side of the bulb (LED actually) from the GAUGES fuse because it's available in run, bulb test, and start conditions. The other side of the bulb goes to the brown/white wire to the PCM to provide ground when required.
When you tried to solder in a replacement that didn't work, did you ensure that you had the LED polarity correct? LEDs only flow current in one direction so if you connect it backwards you'll get no light even if the circuit is working properly. It's unlikely the board contacts are bad unless they have been totally melted during soldering attempts.
Yea, I tried the LED bulb in both directions and it didn't work thats why I think the contacts are bad now. Do I have to get power from the gauge fuse or can it be any ignition on power source? Trying to figure out the wires behind the cluster is near impossible without removing the whole dash and trying to jump the wires from the connector side makes it impossible to reconnect the cluster.
From: Jacksonville, FL (originally from Toronto Canada)
I assume that the inspection will check that the SES light goes on during the startup bulb check so an ignition source won't work for that purpose. If you can't use the GAUGES fuse then a constant (battery) power source would be the next best choice.
so when the schematic says hot in run and start, does that mean it looses power once the car is running? i would assume not since it will need power when a code is thrown. I thought hot in run pretty much meant hot with ignition on/car running ( ie key in run/on position as well as after cranked and running). so wouldn't an ignition switched source be ok since it would be powered as long as the ignition is on and the car running. For example, i have an auxiliary fuse box that's only powered when the car is in acc/start and running. its actually switched with a relay connected to a radio Retained acc power. so it operates like the radio would, getting power with the key in start and running and losing power with key off/removed and door open. would this be a suitable source for power?
From: Jacksonville, FL (originally from Toronto Canada)
When it's hot in run and start, you have power when the ignition switch is in the start position as well as when it's in the run position. Hot in run does not include either while starting or in accessory. If those conditions are true it will say hot in run, start and accy. The other two conditions are "bulb test" and "retained accessory power (RAP)". The radio does not get power while starting... only in run, accy and RAP conditions. Similarly, an ignition power source will not power the SES light during starting or bulb test - the time when you need it most to pass inspection. After all, the inspector isn't going to introduce a fault to see if the SES light goes on while the engine is running. He's just going to cycle the ignition switch to see if it lights up during the bulb test. So unless you can use the GAUGES power or some other circuit which is active during the bulb test, you will need constant power to ensure it lights when needed.
When it's hot in run and start, you have power when the ignition switch is in the start position as well as when it's in the run position. Hot in run does not include either while starting or in accessory. If those conditions are true it will say hot in run, start and accy. The other two conditions are "bulb test" and "retained accessory power (RAP)". The radio does not get power while starting... only in run, accy and RAP conditions. Similarly, an ignition power source will not power the SES light during starting or bulb test - the time when you need it most to pass inspection. After all, the inspector isn't going to introduce a fault to see if the SES light goes on while the engine is running. He's just going to cycle the ignition switch to see if it lights up during the bulb test. So unless you can use the GAUGES power or some other circuit which is active during the bulb test, you will need constant power to ensure it lights when needed.
I see, maybe I just haven't noticed losing lower to my auxillary fuse box during starting. I guess I'll try to see if I can tap into the fuse wire from behind the fuse panel first then just connect to constant power if that is too complicated.
Thanks for all the info.
Finally got a chance to get this light fixed. I tapped into the gauges fuse and the mil circuit on the blue connector on the passenger side. Luckily last time I soldered a bulb into the cluster, I thought ahead and also soldered 2 short wires extending out the rear of the cluster, so I didn't have to take the cluster apart again and just had to use quick connects to link the power and ground wires to the fuse wire and the PCM ground. Easy job, finally passed my emissions.
Thanks for the input.
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Rewire check engine light 
