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XpressKit 451M

Door lock relay module for Python® and Viper security systems

Item #: 607451M

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Get more out of your Python security system with XpressKit accessories. These handy add-ons let you incorporate luxury, security and convenience features into your vehicle.

The XpressKit 451M door lock relay assembly integrates your vehicle's power doorlocks into a Python security system. The pre-wired module features built-in 40-amp relays, and the package includes resistors you'll need to accommodate newer vehicles. Warranty: 1 year

XpressKit 451M Reviews

Average Customer Review:

4 Reviews

Best relay must have

Written by: Mike from San Antonio, TX on June 30, 2015

i have used crutchfield since I was a kid they rock !!! Yes they didn't have it specifically for my vehicle but I called and Brent was awesome !!! He gave me directions plus picture emails to show how it's done !!!

Pros: Made unlock and lock easy as can be . Yes the 100 ohm resister is not in there . Parallel the resistors to drop the ohm load down to 100.

Cons: None

Awesome service !!!

Written by: Mike from San Antonio on June 30, 2015

Crutchfield Customer Review (What's this?)

The below is right they don't have al of the car info on one sheet . How can they !!!! I called customer service and Brent not only told me how to do it but sent emails w picture diagrams !!! I have used crutch field for years and have always received awesome service !!! And yes I am real and not a fake person . Email me soon and I will show proof they care

Pros: Easy to use . Done in minutes

Cons: None

XpressKit 451M

Written by: JohnJ from Hagerstown,Md. on June 27, 2014

Crutchfield Customer Review (What's this?)

Product did not have 100 ohm resistor.Had to provide myself.Product did not include specific wiring diagram for my vehicle {2005 Durango} and a 350i Crime Guard.This caused lost of time and numerous calls to Crutchfield techs before someone finally got it right.

Pros: it works

Cons: missing parts and wiring instuctions for completion

Compact Doorlock Relay

Written by: TomT from Lovingston, Va on November 11, 2012

Crutchfield Customer Review (What's this?)

Installed in a 1998 Toyota Carolla in conjunction with the Crime Guard 350i5 car alarm. This allowed the Car alarm remote to operate the power door locks. My car required the 5-wire setup which involved cutting the factory door lock wires coming from the fuse box so that this was installed in series between the door lock actuator and the door lock switch.

Pros: Wires are more than long enough. Interfaces directly with alarm unit.

Cons: I'm a Electronics Tech so the wire schematics were a little too simplified for my taste.

Hands-on research

What's in the box?

Download owner's manual

  • Micro door lock relay module
  • 27 Resistor multi-pack
  • Installation instructions
  • "Directed Resistor Interface Pack" sheet
  • Vehicle Applications card

Product Research


Overview: The door lock relay module (451M) will interface with most electric power door lock systems drawing 30 amps or less; both relay-controlled and direct-wired reversing-polarity types. It can also drive aftermarket door lock actuators, which must be added in the driver's door of select vehicles. In addition, it can directly operate post-1985 Mercedes-Benz and Audi vacuum-driven systems if driven by a system with selectable-duration pulses (three-second minimum required). The 451M is compatible with the following types of common door lock circuits.

  • Type A: Three-wire (+) 12V pulse controlling factory lock relays
  • Type B: Three-wire (-) ground pulse controlling factory lock relays
  • Type C: Directly-wired (no factory relays) reversing-polarity switches
  • Type D: Aftermarket-actuator-driven systems. These include slave systems without an actuator in the driver's door, but with factory actuators in all the other doors; since these can be controlled with the installation of an aftermarket actuator.
  • Type E: Electrically-activated vacuum systems (Mercedes-Benz and Audi 1985 and newer). This requires special programming of the system.

Resistor Pack: The 451M comes supplied with a 27 resistor multi-pack to interface with various vehicle door locking systems.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Customer Q&A

Crutchfield asked  
Why did you buy this?

It was needed to install the viper alarm. [ Jose  Dec 24, 2015 ]

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