Coyote MIL question

[JohnK]

I had a successful first start of my gen2 coyote today. It's such a huge relief to hear it running after all the work that goes into getting it ready. As others have reported, the first start was completely uneventful - turned the key and it fired up on the first try.

The only thing out of the ordinary that I noticed is that the MIL doesn't appear to be working as I would have expected. When I received my coyote, there was a MIL light in a bracket attached to the OBDII port. I cut those wires and reconnected them to a new LED in the dash (this one (https://watsons-streetworks.com/product/small-chrome-low-profile-led-indicators/)). The coyote MIL had a red and blue wire. The new LED has a red and black wire. I connected the two in the obvious way - red to red, and blue to black. Based on reports by others, I was expecting to see the MIL flash briefly when first turning the key, and then glow slightly when the engine is running. Mine does neither. I've never seen it come on. I checked for codes at the end of the day (3 or 4 starts and letting it run long enough for the fan to turn on). There were no codes stored in memory. I'm wondering if there's an easy way to trigger a code in order to test the MIL functionality? What would be an easy thing to unplug that would throw a code? The MIL is connected via a Molex plug so it would be easy to unpin the connector and switch the wires, if that's worth trying.

Thanks!

[edwardb]

Just to confirm, the MIL is switched on and off by the PCM through the ground wire. The positive lead should have +12V all the time. You should be able to check that with a VOM on the wires from the ODB2 bracket where the light was originally located. The wire with +12V should go to the positive lead on the LED. The other to the ground lead on the LED. And no other ground wires. Yes, the MIL should very briefly flash when initially powered up, and then lightly glow all the time. I've used those same LED's and they definitly glow a little. Pretty much not visible in an open top car during daylight. In my Coupe, I can see it most of the time. It's my "system is on and running" indicator. :p I've had luck triggering a DTC by pulling the connector on the throttle body and starting the engine. Throws a couple throttle body related DTC's. Your code reader should also give an indication of whether the MIL is on or off.

[J R Jones]

I have no experience with this specific issue but I have had issues with LEDs. They can have a delayed "on"; I don't know what your flash frequency is. Some (12VDC) LEDs do not dim; in my experience LEDs do not work on Jaguar XKR (dimmable) instrument illumination.
jim

[JohnK]

After much troubleshooting, it turns out it's a bad LED. I had 13V at the red wire from the coyote harness and 2.5V at the blue wire. I tried swapping wires, tried jumpering with alligator clips to see if perhaps my Molex crimps were bad... no luck. Jumpered in another LED I had sitting around, and it works exactly as expected.

Now for extra credit I get to learn how to clear permanent DTC codes (from disconnecting the throttle position sensor at the throttle body). :(

[edwardb]

After much troubleshooting, it turns out it's a bad LED. I had 13V at the red wire from the coyote harness and 2.5V at the blue wire. I tried swapping wires, tried jumpering with alligator clips to see if perhaps my Molex crimps were bad... no luck. Jumpered in another LED I had sitting around, and it works exactly as expected.

Now for extra credit I get to learn how to clear permanent DTC codes (from disconnecting the throttle position sensor at the throttle body). :(

Good to hear the MIL was something simple. I used those same LED's on my truck and had a couple that were intermittent. Cut away the shrink sleeving and found the workmanship on the wires solder to tabs at the base of the light was very suspect. One was completely separated and only held in place by the sleeving. Took that all apart and re-did them. Yours might be something that simple.

Sounds like that permanent DTC is the result of advice I gave? Sorry if that's the case. I used that method on both my Coyote's without the same issue and always able to immediately clear with the standard delete code function on the scanner. Clearly that's a change and doing a quick search found it's something that's been added to PCM's to prevent cheating on inspections. The write-up I read wasn't specific to the Coyote. But a good bet it's the same thing. https://static.oemdtc.com/GSB/G0000122.pdf

[JohnK]

No worries Paul. I also did a little reading, and apparently permanent DTC's aren't really permanent, they're just a PITA because they can't be cleared the same way as "normal" DTC's. You have to do a universal trip drive pattern or a dedicated monitor cycle (basically drive the car for a certain amount of time) to prove to the ECU that the problem has been fixed. Given that I won't be driving the car for any real distance any time soon, the permanent DTC's may persist for a bit, but they don't trigger the MIL once the current DTC's are cleared. They only show up on the scanner.

Interesting that you also had issues with those LED's. For $8 + shipping I just ordered a new one but for fun I'll take this one apart to see what's going on.