Retro fit keyless entry

[ME TOO 2]

Hello
I have a '98 GMC K2500 Sierra SL; (Ext Cab -2 doors)
The SL, as you know, means the base model.
Manual Windows (crank) & power door locks.

I'm looking for a way to hook up a keyless entry using the existing electric door locks.
Has anyone done this, or know of method that has worked for others?

I think simple momentary contact remote relays sending power to the switched might do the job; but would like to here about mods that have worked.

Thanks
Edward

 

[Svein]

I´ve done exactly that to my car!

My car was originally equipped with an alarm system, so it did not have keyless entry from factory, and the original alarm was ripped out. I was lucky enough to be able to re-use the wires they had already tapped into the door locks with, so it was an easy install on my part, but you can find the wires behind the kick panel on the drivers side. Unfortunately I can´t remember which colours that was tapped into, but I´m sure the12v.com can help you out with the colours!

I used a viper alarm system triggering two separate relays that gave 12v to the original door lock system, but I´m sure you could find a cheap and easy remote system just to do keyless entry. It might be a good idea to wire in a couple of separate relays so the current from the door locks can´t fry your receiver.

Cheers,
Svein

 

[ME TOO 2]

I´ve done exactly that to my car!

My car was originally equipped with an alarm system, so it did not have keyless entry from factory, and the original alarm was ripped out. I was lucky enough to be able to re-use the wires they had already tapped into the door locks with, so it was an easy install on my part, but you can find the wires behind the kick panel on the drivers side. Unfortunately I can´t remember which colours that was tapped into, but I´m sure the12v.com can help you out with the colours!

I used a viper alarm system triggering two separate relays that gave 12v to the original door lock system, but I´m sure you could find a cheap and easy remote system just to do keyless entry. It might be a good idea to wire in a couple of separate relays so the current from the door locks can´t fry your receiver.

Cheers,
Svein

Good idea, Svein
Using the receiver to trigger relays makes a lot of sense.
Now it's time for me to understand exactly how the door lock switches are used in the circuit.

 

[whiteboyslo]

If you already have power locks, it's easy. Kits can be had on eBay and Amazon for as little as $20. Hardest part is figuring out wiring. Check out the website for Bulldog Security. They have some instructions.

Mike

 

[Svein]

If you already have power locks, it's easy. Kits can be had on eBay and Amazon for as little as $20. Hardest part is figuring out wiring. Check out the website for Bulldog Security. They have some instructions.

Mike

Yes - thats definitely the hardest part - figuring where to hook onto the existing car wiring!

In my 98(99 according to vin), the door lock/unlock circuits were two circuits for all doors that you Could hook onto in the drivers side kickpanel by the doors. I have to say I was very happy the day I tested the old alarm wiring on mine with a test wire, and I could trigger the door locks!

You just have to be careful and take your time! Try to probe trough the insulation with a needle or similar before doing any cuts! And spend the time online to look for clues before you start. Reading some documentation upfront can save you a lot of time when actually doing the work!

Once you've got the two circuits you have to splice into, its really easy going!

I chose to buy an alarm and mount it on a relay panel. It has options for remote start and aux outputs for diesel heaters etc. I put it onto a relay board with terminals during the dash above the pedals. It can however be much simpler - Im just an circuits and systems geek!

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[ME TOO 2]

Yes - thats definitely the hardest part - figuring where to hook onto the existing car wiring!

In my 98(99 according to vin), the door lock/unlock circuits were two circuits for all doors that you Could hook onto in the drivers side kickpanel by the doors. I have to say I was very happy the day I tested the old alarm wiring on mine with a test wire, and I could trigger the door locks!

You just have to be careful and take your time! Try to probe trough the insulation with a needle or similar before doing any cuts! And spend the time online to look for clues before you start. Reading some documentation upfront can save you a lot of time when actually doing the work!

Once you've got the two circuits you have to splice into, its really easy going!

I chose to buy an alarm and mount it on a relay panel. It has options for remote start and aux outputs for diesel heaters etc. I put it onto a relay board with terminals during the dash above the pedals. It can however be much simpler - Im just an circuits and systems geek!

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You sure are a circuits geek Svein
That's a nice neat install too!
Thank you to you & whiteboyslo for the good advice

Research in progress
This website has lots of good info (schematics & explanations) on the door lock circuits used by the different auto makers.
https://www.the12volt.com/
They also have a testing scenario for fully identifying the type in the vehicle at hand

Once the weather warms up I will determine what type of circuit is in my '98 K2500
I'm pretty sure the door lock switches reverse polarity at the locking devices
It's a matter of determining how many wires, in what configuration, GM designers chose for the task
Once that's known I'll jump on the project

 

[Svein]

Once the weather warms up? Chicken! haha. No. really. When I don´t have access to a workshop, I tend to put on my proper thermo suit, and then I can play for hours without freezing. I look like a toddler in the kindergarten, but I don´t really care as long as I´m warm. I LOVE my thermo suit!

Anyway, I am fiddling with mounting towing mirrors today - running the cables for extra lights and stuff trough the hole behind the kick panel I was talking about, and then I was thinking of you, so I shot a couple of photos of the two circuits on my car. It´s a 1999 model suburban according to the VIN, but it was imported and on the road late 98 according to the DMV, so maybe it´s the same in your truck?

When it comes to polarity, I am adding feeding positive to the door locks.

Blue and white seems to be the colours on my truck:

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Close up of the plug they snipped it from:

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Where the cables are located:

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