relay wiring, fuel and pcm

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=129417
Printed Date: May 20, 2024 at 6:05 PM

Topic: relay wiring, fuel and pcm

Posted By: daflipcyde
Subject: relay wiring, fuel and pcm
Date Posted: November 28, 2011 at 2:07 AM

Installing Remote Start Compustar CM5000 Module. Ground when running wire output is 250ma

I have an aftermarket immobilizer that disables
1) Fuel
2) PCM

Looking at it, both fuel and pcm wires are cut (separated). Each cut end has a wire that goes to the brain of the aftermarket immobilizer. How do I wire up the relays to make each fuel and pcm wires get connected while in remote start?

I'm guessing I need 2 spdt relays for each. How do I get the wires joined while in remote start?

Replies:

Posted By: daflipcyde
Date Posted: November 28, 2011 at 2:19 AM

I want to have continuity on the fuel wire and continuity on the pcm wire

Posted By: i am an idiot
Date Posted: November 28, 2011 at 2:58 AM

Knowing more about the immobiliser may make it easier for both of us. Not knowing more about it, it will take 3 relays to make this happen. Wire as follows. Relay 1 GWR to 85. Constant power to 86 and 30. 87 goes to 86 of the 2 other relays. Ground 85 of both of those relays. PCM relay, one of the "cut / separated" wires to 87, the other wire to 30. Fuel relay, one cut / separated wires to 87, the other wire to 30.

It may be easier to disable the immobiliser while under a rem start situation.

Posted By: howie ll
Date Posted: November 28, 2011 at 7:57 AM

X 2 with Mr. Idiot, also I firmly fuel and PCM cuts are inherently unsafe for instance a bad joint that opens up on acceleration or cornering.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: daflipcyde
Date Posted: November 28, 2011 at 11:13 AM

Ok I will try that. Thanks.
What the immobilizer does once armed it cuts power to the fuel and pcm. Without a FOB when you try to start the car it is completely disabled. The FOB sends a signal to the immobilizer and energizes the relays inside and closes the fuel and pcm circuits.

So what I want to do is go right to the cuts where the aftermarket immobilizer went. Get the remote start to temporarily defeat the aftermarket immobilizer.

So with 3 relays it should work how you described it?

Posted By: i am an idiot
Date Posted: November 28, 2011 at 1:40 PM

Yes.

Posted By: daflipcyde
Date Posted: November 28, 2011 at 4:23 PM

Ok I tried the setup you told me. It doesn't seem like its working. The relays doesn't seem to get energized. I checked for voltage I'm getting 12 volts on power wire and ground is good. I checked voltage on GWR and I only get like 3 volts when I try to start vehicle. Is that enough to get the relays going?

I'm using spst 40 amp relays and the power is fused at 10 amps.

Posted By: howie ll
Date Posted: November 28, 2011 at 5:19 PM

OK here's how to do it using 2 relays.:-
immob_by-pass.bmp

Use the GWR wire, note the 2 x 1N4004 diodes, one for each relay.
Using a DMM, find the immobiliser module and find the two wires that go live with the ignition on after you turn off the immobiliser marked as outputs in the diagram, join them to each relay output (30).
N.B. If you have a bypass and the GWR is controlling it, use another diode to separate them.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.