do i need to use diodes here?
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=113651
Printed Date: April 28, 2024 at 12:23 PM
Topic: do i need to use diodes here?
Posted By: proximity
Subject: do i need to use diodes here?
Date Posted: May 07, 2009 at 12:06 AM
I'm installing a Viper 5901 in my 2001 toyota celica and I'm wondering if I'll need to use diodes here.
For the 5901, there are 2 wires which control (un)locks:
1 BLUE (+) LOCK (-) UNLOCK OUTPUT
3 GREEN (-) LOCK (+) UNLOCK OUTPUT
And looking at the door lock control pdf from the electircal manual for my car, there are two wires going into the body ECU from the lock/unlock switch, a blue/white wire which controls the locking and a pink/black which controls the unlocking. Either of them need to be grounded for the operation to function.
Since the blue 5901 wire sends a negative pulse on unlock, I'm thinking that I can connect that to the pink/black wire from the switch. And then using the same logic, connect the green 5901 wire to the blue/white wire from the switch.
I'm just worried that the positive pulse that is also sent will mess things up. Will I need to use diodes?
Replies:
Posted By: howie ll
Date Posted: May 07, 2009 at 2:38 AM
The diodes aren't really neccessary on this application, BUT that particular output can be strange, I would use them to "make sure" the lock unlock wires only get a neg signal from the 5901, thus you won't be responsible for any possible damage to the lock ECU. Diode bands towards 5901.
Posted By: KPierson
Date Posted: May 07, 2009 at 5:29 AM
You can also measure the voltage at rest of the lock/unlock wires. If they rest at 12vdc then obvisously 12vdc on the inputs won't hurt them. If they are 5vdc or open at rest it wouldn't hurt to install the diodes.
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Kevin Pierson
Posted By: howie ll
Date Posted: May 07, 2009 at 7:07 AM
You can also get spurious voltage spikes, this may be enough to overcome the unit's lock/unlock outputs, I've seen that on various cars here, that's why installers prefer relay driven lock/unlock outputs, more wiring, less problems, in fact DEI now recommend you always use diodes, in fact the biggest selling Clifford unit worldwide (not sold in North America) was xchanged to the Mk ll last year with amongst other things relay lock outputs. Be safe and sure use them. Also if you don't get ignition lock, go to lock relay *I think it's still a relay vertically mounted behind or under dash, find the lead which goes to ground when the driver's door is opened , cut and ground the lock relay side.
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