Blazer door lock isolation?

Hi all,

I am isolating BOTH door locks in my '01 Blazer, 2 door SUV. Driver priority will be configured with the alarm. I am doing this so that when disarm is pressed once, the driver unlock motor will unlock BUT THEN, when disarm is pressed again, ONLY the passenger door will unlock (not both locks). I know its a little more work but I just like it done this way. I have done this on all my vehicles and it works nicely.

On all the other vehicles I did it on, there was a B+ line somewhere in the door harness wires behind the door panel. This wire is needed to both energize the relay and provide juice to the door lock motor.

My question is: where do you get the B+ line on this vehicle? I don't want to have to drag an entire wire just for B+ if there was one in the door. I metered everywhere and only found a very small gauge, orange wire. I dont remember having this headache with other vehicles; i thought there was B+ somewhere in the door lock harness.

Thanks!
John

You should be able to do that at the Relay Block under Driver Dash above & between Brake Pedal & Emergency Brake or @ BCM

RKE Module	BCM IN FRONT OF CENTER CONSOLE
Motor Lock	GRAY	AT RELAY BLOCK UNDER THE DASH *
Motor Unlock	TAN	AT RELAY BLOCK UNDER THE DASH *
Drv Door Unlock	TAN	AT RELAY BLOCK UNDER THE DASH *
OEM Relays	IN BODY RELAY BLOCK UNDER DASH

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MO

Don't Learn from Others Mistakes
You Might Be the One That Knows.

Thanks Mo, thats a good idea. I did run into a problem though. the tan lock motor wire rests at ground. I found that out by putting 12v on that wire and got a big spark. I probably came very close to blowing a fuse. I dont know how in the world you isolate these locks if the unlock wire rests at ground??

So, does anybody know the unlock wire colors for EACH door (driver and passenger) that come out of the BCM? There are three plugs in the BCM (if my memory is not failing, they're blue, purple and brown) If you happen to know the pin location in which plug that would be excellent.

Thanks!
John

As Posted:
5 wire Reversal for Driver & Passenger

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MO

Don't Learn from Others Mistakes
You Might Be the One That Knows.

Wouldn't going straight to the BCM be the easiest? Not having to hook up extra relays and stuff.

The '01 Blazer does have individual unlock wires for each door coming out of the BCM doesn't it?

The vehicle has factory driver priority locks so I would think these wires are at the BCM

John

The design of that Blazer is such that the wires coming from the BCM are actually viewable on the left side of the center console, but are neatly taped up----not very elegant, but it works.

In my opinion, if you cut that harness open and add wires and whatnot, you'll have a hard time getting it taped up again in a way that looks nice.

If you've already opened up the harness anyway, go ahead and find the driver-unlock wire there, 5-wire it, and be done.

Or, if it were me.......up above the part of the parking brake pedal where your foot would touch, is a large plug with the wires facing down; I always get my locks and factory-disarm right there. It wouldn't surprise me if the driver-unlock-motor wire were available there as well.

Chris Luongo wrote:

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Or, if it were me.......up above the part of the parking brake pedal where your foot would touch, is a large plug with the wires facing down; I always get my locks and factory-disarm right there. It wouldn't surprise me if the driver-unlock-motor wire were available there as well.

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It is & same here

still a 5 wire reversal

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MO

Don't Learn from Others Mistakes
You Might Be the One That Knows.

Can someone please verify for me whether the BCM has these 3 wires:

- Lock (all doors)
- Unlock (driver door)
- Unlock (passenger door)

These wires would trigger a small negative signal when operated which would presumably energize their respective relays which in turn give juice to the lock in the door.

Nobody has yet to answer this.

Thanks.

The light green terminal A4 on BCM connector C2 (blue) does driver door by itself with a negative input (-) if I am reading my diagram correctly- always test wires first...

The lt blue wire on terminal A4 and the white wire on terminal A3 of the BCM connector C1 (brown connector) with +12V applied  will do lock and unlock functions of all doors-

The passenger door cannot be unlocked while the driver's door remains locked- but the driver's door can be unlocked while the passenger door remains locked

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Brcidd - Engineer That Does Remote Starter Installs on the side.

In reference to the relay pack above the parking break: Is there a separate relay for the driver door AND passenger door? If so, I could tap into which ever wire energizes each relay.

I'm thinking there are two because the car can control the driver and passenger door locks separately. If both locks were hard wired to the same relay, controlling them separately would be impossible.

Anyone know if there is a relay for each door in the relay pack?

--I believe the relays would be internal to the BCM, with no low-current negative pulses available anywhere that you can access. If you want driver's-prirority unlock, you'll have to 5-wire it witn your own relay.

You can always verify this by listening for which parts click when you operate the locks.

I find that if you hold a screwdriver or other tool firmly against a particular part, you can be more sure than just doing it by ear.

--Up above the parking brake, I think that's just a junction plug, not a relay bank.

Hi Chris, the relays are in a relay pack above the parking brake. I verified this today and pulled them down (what a pain). The user named brcidd was VERY helpful in sending me the GM wiring schematics for the relay pack circuit. As suspected, it has a separate relay for each: lock (all doors), unlock (driver only) and unlock (ALL doors).

The problem is that the third relay mentioned above unlocks ALL the doors (which is equivalent to what happens during the 2nd push of the unlock button on the factory remote)

I am too anal and dont want that...lol. So, I can just tap into the driver unlock only relay with the first unlock alarm output. The second alarm unlock output, however, will be different. Normally it would open all the door locks. I want it to only open the passenger door only. That way the driver door motor doesn't get unlocked twice needlessly. That means I will in fact have to isolate the unlock wire but only to the passenger door, not both doors as others have said.

I think this should work for that:

85 - B+
86 - 2nd alarm unlock output (-)
87 - B+
87a - tan unlock motor wire (going to relay pack)
30 - tan unlock motor wire (going to lock motor)