Wiring Harness Questions

[PaulPerger]

Several of my wiring labels have faded or fallen off and I am left with several questions. I'll start with these two items. They were tagged before I removed them from the Cobalt but my code sheet was ruined so I don't know what everything is.

Can someone identify these?

 

[Ross]

They might be in the instrument panel video here, but I don't recognize them by looking at them.

 

[Rttoys]

The first one Looks like the TPMS module.

The second one might be the ambient light sensor?

 

[Jareth]

To me the second one looks like the sensor that turns the head lights on when the sun goes down, it is missing the little dome on it.

On a donor it would been on and sticking out of the top of the dash a little.

 

[Rauq]

Looks like it.

 

[ah.b.normal]

I've got a sensor if you can't find one. Message me with your address and I'll mail it to you. Cover shipping, about $10.

 

[PaulPerger]

I think you all are correct on both accounts.

Do we need the Ambient light sensor? If I just cut it out, is that going to mess with the lighting system? I never use “Auto Mode” on lights anyway.

And the same with the TPMS… Will cutting it out cause an error code? Actually, better question, will cutting it out cause something else to not work?

 

[Rauq]

I think on LSJs that's just for the remote unlock, the LSJ's didn't have TPMS. I think there's a similar module on other models that is TPMS and remote unlock together. No consequence in removing it, I don't have mine.

I believe without the ambient light sensor the car will always think it's dark and turn the low beams on... but I might have that backwards. It's been a while since I didn't have mine plugged in.

 

[Sebnuts]

If the light sensor is not installed, it will just default to lights on if in "Auto Mode" and won't cause any other issues.

Not sure about TPMS removal.

 

[PaulPerger]

I think on LSJs that's just for the remote unlock, the LSJ's didn't have TPMS. I think there's a similar module on other models that is TPMS and remote unlock together. No consequence in removing it, I don't have mine.

I believe without the ambient light sensor the car will always think it's dark and turn the low beams on... but I might have that backwards. It's been a while since I didn't have mine plugged in.

I didn’t remember having TPMS, but it’s been 18 months since I drove it, so I figured I just didn’t remember it. I think you might be right though. The images I am seeing online for that part look like it is the Remote Fob Sensor.

 

[ah.b.normal]

Having worked on repairing several of the Cobalt/Goblin wiring harnesses, My position is "abandon in place"(Insulate with tape and wrap them into the harness) any unused connectors that DF did not have us delete.
As manufactured there are subsystem connectors present in harnesses unused and taped aside; example, in the body harness there is a plug to the Automatic shifter(neutral safety switch) that is present(abandoned in place on manual applications); in the dash harness there is the same connector that is the neutral start switch on the clutch pedal(abandoned in place on automatic applications) in the harness. The BCM is programed as to which to use. I do not like BCM but I know if it's in there we must keep it "happy"! When a BCM is "not happy" it takes hostages, I.E.: refuses to turn stuff/lights on or off, or even close the windows or turn on the radio amplifier.

(CAUTION: RANT: BCM is not a friend of mine. I think the BCM in my RV has a red stapler. RE: Office Space)

 

[Rttoys]

It has tpms, it’s just not as sophisticated as the 08 and up. Both can be deleted if you want.

 

[Rauq]

It has tpms, it’s just not as sophisticated as the 08 and up. Both can be deleted if you want.

Is it the differential wheel speed sensor system? Where it says 700-700-700-665 rpm wheel speeds means one tire is 5% smaller and therefore probably low?

 

[Rttoys]

That, I don’t know. I know my 06 doesn’t care if it’s plugged in or not, but JBINTX 09 starts flashing things on the dash if his isn’t working.

 

[Robinjo]

That, I don’t know. I know my 06 doesn’t care if it’s plugged in or not, but JBINTX 09 starts flashing things on the dash if his isn’t working.

I don't think I have one in my 06 based Goblin either. All that has happened to me is I have an annoying light on my dash.

 

[Desert Sasqwatch]

I'm trying to understand how individual wheel speeds can be determined from a single speed sensor that's measuring the transmission output? Unless you have the ABS wheel speed sensors still in your wiring harness, I'm not seeing that's possible.

TPMS works off of radio frequency transmitters inside each wheel that include an air pressure sensor switch. These transmitters have a 3-5 year battery life - usually - and the TPMS reads the pressures directly from the RF signals. The TPMS has to be mounted in the correct orientation to be reading the individual corners accurately.

 

[Brett]

I'm trying to understand how individual wheel speeds can be determined from a single speed sensor that's measuring the transmission output? Unless you have the ABS wheel speed sensors still in your wiring harness, I'm not seeing that's possible.

TPMS works off of radio frequency transmitters inside each wheel that include an air pressure sensor switch. These transmitters have a 3-5 year battery life - usually - and the TPMS reads the pressures directly from the RF signals. The TPMS has to be mounted in the correct orientation to be reading the individual corners accurately.

Actually, when you associate the tpms sensors to the car, you do it in a specific sequence so that the sensors and the car know what sensor is in each tire. The receiver does NOT have to be in a specific orientation to know which sensor is where. Basically, the sensor has an identifying code that the car knows which corner it is in based on the sequence the sensors are detected.

I dont want to make a blanket statement that this is how all tpms systems work but on the cobalt that is how it works. At least on my 2009.

 

[PaulPerger]

Having worked on repairing several of the Cobalt/Goblin wiring harnesses, My position is "abandon in place"(Insulate with tape and wrap them into the harness) any unused connectors that DF did not have us delete.
As manufactured there are subsystem connectors present in harnesses unused and taped aside; example, in the body harness there is a plug to the Automatic shifter(neutral safety switch) that is present(abandoned in place on manual applications); in the dash harness there is the same connector that is the neutral start switch on the clutch pedal(abandoned in place on automatic applications) in the harness. The BCM is programed as to which to use. I do not like BCM but I know if it's in there we must keep it "happy"! When a BCM is "not happy" it takes hostages, I.E.: refuses to turn stuff/lights on or off, or even close the windows or turn on the radio amplifier.

(CAUTION: RANT: BCM is not a friend of mine. I think the BCM in my RV has a red stapler. RE: Office Space)

I like the Abandon In Place concept. I think ill do that and leave about 3inches of wire sticking out of the loom in case I figure out I need them later…

 

[Desert Sasqwatch]

Actually, when you associate the tpms sensors to the car, you do it in a specific sequence so that the sensors and the car know what sensor is in each tire. The receiver does NOT have to be in a specific orientation to know which sensor is where. Basically, the sensor has an identifying code that the car knows which corner it is in based on the sequence the sensors are detected.

I dont want to make a blanket statement that this is how all tpms systems work but on the cobalt that is how it works. At least on my 2009.

Thanks Brett, good to know if (when) I get to this step in my build...someday.