CEL, GMPP harness for LS3

[DT69Cam]

Does anyone know if the "Check Engine Light" on the GMPP LS3 harness is triggered by a negative source ?? My new gauges CEL needs a positive trigger for the light to turn on. I know I need a relay to convert from neg to positive. I just wanted to confirm the negative source for the CEL. Thx.

[130fe]

What gauges are you running? I am currently running the VHX gauges and just have the CEL wire from the GMPP bulkhead wired directly into their control box. I used the have an LT1 (before the LS3) using an another companies EFI harness and it did provide the negative side of the circuit from the PCM side. I just had to hook the other side of the LED to an IGN source.

[TomM]

Typically you supply the CEL with a keyed/fused +12V circuit. The ECM switches a negative signal to the CEL when a DTC is set. Easy way to check if you have HP Tuners is to toggle the CEL with the software.


T,

[DT69Cam]

Thanks guys for the reply. I'm using New Vintage Gauges 69 series 3 in 1. The gauges call for a positive trigger (12V) on the warning lights. I know the parking brake is triggered via a ground. I will be using a relay to convert neg to positive for the brake light in the gauge. I also think the CEL is triggered via a ground, so in order for the CEL to light up in the gauge I have to convert it to positive, (another relay).

[dhutton]

Thanks guys for the reply. I'm using New Vintage Gauges 69 series 3 in 1. The gauges call for a positive trigger (12V) on the warning lights. I know the parking brake is triggered via a ground. I will be using a relay to convert neg to positive for the brake light in the gauge. I also think the CEL is triggered via a ground, so in order for the CEL to light up in the gauge I have to convert it to positive, (another relay).

I am not sure that the CEL signal can drive a relay. What is the coil resistance of the relay you are using?

Don

[DT69Cam]

I am not sure that the CEL signal can drive a relay. What is the coil resistance of the relay you are using?

Don

You know Don I am not exactly sure. Typical 30a Bosch relay. The relay is just converting from negative to positive trigger (reverse polarity)

[dhutton]

You know Don I am not exactly sure. Typical 30a Bosch relay. The relay is just converting from negative to positive trigger (reverse polarity)

I guess you can try and see if it works. 30A is a bit of overkill for this application. :D

Something like this is all you need:

http://www.ebay.com/itm/2pcs-Blue-4100-DC12V-SHG-SRS-12VDC-SL-12V-small-signal-relay-6pin-RL401-1-/301726097534?hash=item464046e07e:g:8mQAAOSwT6pV4XR o

Don

[DT69Cam]

I guess you can try and see if it works. 30A is a bit of overkill for this application. :D

Something like this is all you need:

http://www.ebay.com/itm/2pcs-Blue-4100-DC12V-SHG-SRS-12VDC-SL-12V-small-signal-relay-6pin-RL401-1-/301726097534?hash=item464046e07e:g:8mQAAOSwT6pV4XR o

Don

I agree the 30a is overkill. That small signal relay looks pretty good. Hmmm.

[dhutton]

I agree the 30a is overkill. That small signal relay looks pretty good. Hmmm.

You could also use a simple single transistor inverter. Not sure if you are comfortable with wiring something like that. I have the same gauges and will go that route when I finally get to wiring them up.

Don

[dhutton]

This Bosch 12V 30A relay has a coil current of 160 mA which is a lot more than an LED.

http://www.texasindustrialelectric.com/relays_0332209150.asp

I will dig around and see if I can find the CEL current capability.

Don

[DT69Cam]

This Bosch 12V 30A relay has a coil current of 160 mA which is a lot more than an LED.

http://www.texasindustrialelectric.com/relays_0332209150.asp

I will dig around and see if I can find the CEL current capability.

Don

Thanks Don !!!! So the Bosch relay may work ??

[dhutton]

Thanks Don !!!! So the Bosch relay may work ??

No I think it requires considerably more current than an LED and as such it may not be able to sink enough current to turn the relay on.

This is all I could find regarding MIL current capacity:

This circuit requires any 12v low current light and an ignition 12v power source. The ECM MIL output supplies the ground for the circuit.

I am not sure that 160 mA would be considered a low current light.

Looks like all you can do is try it and see if it works. Sorry I could not be of more help other than raising questions.

Don

[DT69Cam]

No I think it requires considerably more current than an LED and as such it may not be able to sink enough current to turn the relay on.

This is all I could find regarding MIL current capacity:

This circuit requires any 12v low current light and an ignition 12v power source. The ECM MIL output supplies the ground for the circuit.

I am not sure that 160 mA would be considered a low current light.

Looks like all you can do is try it and see if it works. Sorry I could not be of more help other than raising questions.

Don
Hey, thank you very much !!! FYI Don, I'm also over on Team Camaro. I asked the same questions over there LOL. Thx again.

[dhutton]

How about this little solid state relay? If I am reading it right you can use a positive or negative trigger. Just connect the negative trigger input to the MIL signal and add a 4.7kohm pull-up resistor to 12V. Then use the relay as you had planned.

http://www.ebay.com/itm/1-Channel-SSR-Solid-State-Relay-high-low-trigger-5A-5v12v-For-Arduino-uno-R3-/331651616280?hash=item4d37fa0e18:g:b0QAAOSw4SlV8f4-

Don

[randy]

why can't you just give the light constant power and hook the ground to the check engine light wire? Thats what i did

[130fe]

Don, just curious. The picture I saw on New Vintage's website showed a CEL in the right side gauge. Why not use the one already built in? Are you 100% sure that the CEL requires the POS signal? Just seems weird that the industry standard is a Neg signal from the PCM and New Vintage is totally different. Just seems like alot of trouble to go through for the light to work.


http://www.newvintageusa.com/images/69-set-lit.jpg

[DT69Cam]

Don, just curious. The picture I saw on New Vintage's website showed a CEL in the right side gauge. Why not use the one already built in? Are you 100% sure that the CEL requires the POS signal? Just seems weird that the industry standard is a Neg signal from the PCM and New Vintage is totally different. Just seems like alot of trouble to go through for the light to work.


http://www.newvintageusa.com/images/69-set-lit.jpg

Yep, that's the one. It calls for 12V positive.

[dhutton]

Don, just curious. The picture I saw on New Vintage's website showed a CEL in the right side gauge. Why not use the one already built in? Are you 100% sure that the CEL requires the POS signal? Just seems weird that the industry standard is a Neg signal from the PCM and New Vintage is totally different. Just seems like alot of trouble to go through for the light to work.


http://www.newvintageusa.com/images/69-set-lit.jpg

For whatever reason the gauge wants a positive drive for all the indicators. Both LED pins are not brought out, only the positive side as far as I know. Why they didn't do their homework is a bit of a mystery. There may even be a controller between the input signals and the LED's.

Don

[dhutton]

why can't you just give the light constant power and hook the ground to the check engine light wire? Thats what i did

Because you don't have access to both LED pins.

Don