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Hood Switch Testing - Need help!

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Old 01-10-2010 | 03:51 PM
  #1  
e_leska's Avatar
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From: Minneapolis
Hood Switch Testing - Need help!

Wondering if someone with a 2008 HHR could make an electrical test?

Is there any way someone could pop open their hood, disconnect the hood switch connector (assuming you have remote start) and check for continuity between the 3 wires on the hood switch with the latch in all 3 positions (closed, latched but ajar, fully open)?

It would also be helpful to check voltage on the switch by probing the back of the connector plugged in....mainly when the latch is closed, what is the voltage on the purple wire.

We have tested a 2008 HHR LT that chevy claims cannot have remote start "added" with a SnapOn tester that shows the remote start system is functional but disabled due to the hood being "ajar."

However, HHR's meant for rentals are missing the AP3 option that allows remote start to function. After quite a few go arounds with Chevy, we've determined AP3 is simply an alternate front wiring harness assembly and hood latch with switches and nothing else. This is what they consider "Remote Start Ready."

We now have a FOB programmed that flashes running lights when the remote start signal is sent, the DIC shows remote start is enabled, but the hood switch issue still remains.

Knowing how the 3 switch wires behave would allow us to jumper the front harness connector behind the drivers headlight area and then scan with a SnapOn tool to see if the hood ajar is resolved and the RVS system gets closer to starting.

If someone could take 10 minutes with a VOM and test the switch, it would be greatly appreciated! Maybe we can end up helping others at the same time.

Thanks!
Old 01-10-2010 | 04:12 PM
  #2  
oneton's Avatar
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Have you tested the switch to see if shows open and closed ? Also have a dealer print out a build sheet and it will show if remote start is there or say deleat.
Old 01-10-2010 | 04:40 PM
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I have a ex-rental too, so can't help with the VOM. Does the existing harness even have the wires for the switch? Or is the AP3 harness an extension from a blank connector, that would be too easy?
Old 01-10-2010 | 04:54 PM
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I found a wiring diagram for a 2006 that shows Purple from the switch goes to pin 3 on the BCM, PNK/BLK goes to pin 4 on BCM. and BLK goes to ground on the shock tower. Is that any help? that seems to mean ground PPL and PNK/BLK to give a closed signal.
Old 01-10-2010 | 05:06 PM
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that would be in HHR2.rar in this topic https://www.chevyhhr.net/forums/deleted-threads-41/my-hhr-links-r-here-hhr-tech-manual-24774/
Old 01-10-2010 | 05:40 PM
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e_leska's Avatar
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It would be handy to have actual confirmation of how the switch operates seeing as two of the wires go directly to the BCM.

I'd feel more comfortable knowing how the switch works before twisting wires together that have voltage on them.

The diagrams show the PK/BK wire and the PU wire both close to the ground wire when the latch is in one direction. This came from AllData diagrams.

The AP3 distinction is a different front end harness and electronic hood latch. This makes the car "Remote Start" ready.

The X121 "Forward Lamp Harness To Body Harness" connector at the front drivers side engine compartment has the 3 "AP3 Hood Switch" wires in it on the body side (connector is to the outside of the brake line proportioning valve). I've tested these wires and PK/BK shows 12v+ whereas the signal wire PU gives off an odd 0.5v signal. The front bumper end of the non AP3 harness has rubber plugs in those 3 wire locations.

It would be easy to jump the wires right at the body connector if we were sure what switch does with the 12v+ signal. The forward lamp harness is very basic as well. I'd bet you could order one from Chevy if you were hard pressed to have OEM setup, but in my case I could care less about the hood switch if the RVS works by jumping two wires.
Old 01-10-2010 | 05:53 PM
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e_leska's Avatar
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Originally Posted by donbrew
I have a ex-rental too, so can't help with the VOM. Does the existing harness even have the wires for the switch? Or is the AP3 harness an extension from a blank connector, that would be too easy?
Yes, I'm betting it is that easy. Chevy had two part numbers for forward lamp wiring harness, one with AP3 electric hood switch and one without. It covers the running lamps, airbag sensor and hood switch.

Every time you see wiring diagrams or hood latch descriptions in parts or tech manuals on the HHR, you see the code AP3 next to the wire or part. AP3 doesn't appear anywhere else on wiring or modules, except when related to "hood ajar/hood closed" signals.

After researching this and sorting through the abyss of disinformation from Chevy techs from a half dozen dealerships in Minneapolis area, it looks like the RVS on an ex-rental car comes down to having the correct programmed key FOB and hood switch circuit in place.
Old 01-10-2010 | 06:05 PM
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Originally Posted by oneton
Also have a dealer print out a build sheet and it will show if remote start is there or say deleat.
Build sheets.....

Literally 6 local dealerships contradicted each other on how this works. Some said "remote start" would be listed, some said if it was part of the LT package it wouldn't be listed separately, some said they'd seen AP3 on the RPO in the car and "Remote Start/Remote Start Ready" not listed on the build sheet.

In one case, a service tech ran a build sheet on an HHR sitting in the shop that had a working remote start to see what came up. Remote start wasn't listed anywhere, which he said confirmed that it wouldn't be listed by itself if part of a package.

Of course everyone was willing to charge me an hour labor to put the Tech2 on it and "see what it has."
Old 01-10-2010 | 06:06 PM
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Well, then won't they sell you the switch, and then make your own harness? or junk yard? And the odd +5V leads me to believe Logic Level Signals.
Old 01-10-2010 | 06:11 PM
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yes the build sheets are misleading. My ex-rental says no RKE, but that turned out to be just getting a tech who knew what he was doing to reprog the BCM, that took 5 trips to the dealer. now have RKE and can reset TPMS by myself!



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