04 jeep grand cherokee parking lights

I have installed a viper 5101 remote start and a DEI XK531 transponder / lock control bypass.

My issue: I can't find a way to make my parking lights stay constant when in remote start mode if the light switch is in the automatic mode.

However I can send a negative to the flasher relay and cause them to flash, this I cant stand nor my neighbors.

Currently I have a negative pulse with a 1300ohm resitor running to the yellow wire at light switch. This provides constant lights on ONLY when light switch in off position (So no auto Lights on while driving)

I have attached a wire to the parking light relay pin 30 and get the same effect.

Anyone know how I can keep the switch in the auto on light position and turn my lights on during remote start mode?

Thanks in advance!



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JC

Did you isolate the switch with the WHITE/ brown wire? If not,

Cut the wire in half, connect your white wire to switch side and the WHITE/ brown wire to the other side. Put your resistance in the negative fuse spot and fuse the line elsewhere.

I am confused as to what wire I am suppose to connect the non switch side? I am using a viper 5101 so my white wire has adjustable polarity via a fuse link under a cover on the unit, so i only Have one wire from the viper unit. What is the function of the WHITE/ brown wire. I am assuming it is in the harness at the column with the yellow parking light wire and the blue/pink flasher wire?

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JC

The yellow parking light wire(on vehicle) needs to be cut - connect the WHITE/ brown(from Viper) to the switch side of the cut wire, and the white(from Viper) to the side facing away from the switch.

The purpose of the WHITE/ brown is specifically for controlling the parking lights on Chrysler products with resistance switching parking light circuits. On these vehicles, like your Jeep, instead of having a switch which directly powers the parking/head/fog lights, the switch sends a negative-through-varying-resistors signal to the Body Control Module, which then activates the lights.

Basically, when the Viper is not activating the parking lights, the switch on the vehicle functions normally. When the Viper activates the parking lights, it cuts off the resistance signal from the switch and tells the BCM to turn the parking lights only on.

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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two

After reading through the forum I found a tech tip from autocommand that requires breaking off pin 84a relay. I did do this so will i need to replace that relay?

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JC

Sorry I meant 87a.

chriswallace187 you where exactly right everything functions fine now. I did have to replace the relay with one that had a 87a pin.

Thanks for your help!

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JC

Excellent...glad to hear it!

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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two

Sorry to resurrect an old post, but I am looking to accomplish the same thing on my 2002 Grand Cherokee with Auto headlights. However, I have a compustar 6200 brain and it does not have the equivalent (to my knowledge) of the BROWN / white wire on the Viper.

Is there a way I can leave the lights set to auto and have only the parking lights come on during remote start with the compustar?

Thanks,

Jason

lilngineer,

Yes, it's doable. You just have to use a separate relay controlled by the parking lights wire from the brain.

I'm not sure exactly what parking light outputs that Compustar model has, but here's 2 ways of wiring the relay. First, if you have a positive parking light output:

86: positive light flash output from alarm
85: ground
87: ground, with a 1300 ohm resistor wired inline. Also as I always recommend, cut a piece of cable tie and tape it lengthwise along your resistor connection to help prevent the resistor from breaking.
87a: cut the yellow multiplex lights wire and connect this pin to the side facing towards the light switch.
30: yellow lights mux wire, side facing away from the switch.

If you only have a negative light output from the Compustar:
87, 87a, and 30 are connected the same way as above.
86: 12 volt constant fused
85: negative light flash output from alarm

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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two

Chris,

Thanks for the help. My compustar has both negative and positive triggers.

Compustar sent me a Fortin diagram that showed the positive trigger setup you mentioned, however on the diagram it says that the parking lights will not work in the auto setting.

Do you know if this is true?

Jason,

You'll notice in the instructions that I gave you that the yellow light switch wire is cut and connected to the relay's 87a(normally closed) and 30(common).

What this does is isolate the light switch from the BCM when the aftermarket unit is controlling the parking lights via the relay. All the BCM will see is the 1300 ohm resistor you've added on, and it should interpret that as "parking lights".(See my above comment for explanation if you haven't already.)

If I'm guessing correctly, that Fortin diagram has 30 going to the uncut yellow light switch wire, 87 to ground, and a resistor worked in somewhere. That install method does not isolate the light switch - and when the switch is turned to the "auto" position it supplies ground through a lower resistance value than what the value would be in the "off" position.

Now I'm going all-out electronics geek with the next several paragraphs, because I think this is a great opportunity to illustrate a principle of electronics, but I'll give you the short answer first: It's true that the parking lights won't work in the "auto" setting - if I've guessed correctly what Fortin is suggesting you do. If you follow my instructions above, the parking lights WILL work when the remote start orders them on, regardless of what position the light switch was left in. I've wired it that way on many Chrysler products with automatic headlights, and it's always worked. Read on for an explanation if you like...

First off, the formulas for calculating resistance with multiple resistors(let {R1, R2, R3,...,Rx} be the values of the resistors in ohms):
Resistors in series: R1+R2+R3+...+Rx
Resistors in parallel: (R1*R2*R3*...*Rx)/(R1+R2+R3+...+Rx).

Those are the general formulas. Now what you're dealing with specifically on a Chrysler with a multiplex light switch is a set of several resistors built into the switch. Let's call them A, H, P, and Q for "auto", "headlights", "parklights" and "off" respectively. Let's also say you're adding a resistor (call this one V) somewhere in the wiring involved with your aftermarket remote starter/alarm/keyless entry unit.

If you use a relay with the yellow switch wire cut, 87a going toward the switch, 30 going toward the BCM, and 87 going to ground through resistor V, the BCM will only ever see resistance V when the relay's active regardless of which position the switch was left in, since the other resistors are now not involved in this circuit.

If you connect resistor V from ground to the yellow switch wire, via a relay or the aftermarket unit's (-) output, you've now got a parallel resistor math problem. The resistance value that the BCM sees is going to be, in accordance with the above formula, one of the following values:
(V*Q)/(V+Q)
(V*P)/(V+P)
(V*H)/(V+H)
(V*A)/(V+A)

At this point, a side note is appropriate. When dealing with 2 resistors of differing value in parallel, where the larger resistor is an order of magnitude or more higher than the smaller resistor, the total resistance of the circuit will be very close to the value of the smaller resistor. Feel free to use this parallel resistance calculator from the site to see how this works in practice.

Back to the specific case of a Chrysler vehicle with a headlight switch like this - I don't know all of the values in question. However we can say that Q is greater than P, P=1300 ohms, H=330 ohms, and A is less than H.

When resistor V, also 1300 ohms, is added to this circuit (i.e. when the aftermarket unit tries to flash the parking lights), generally this will result in either (V*Q)/(V+Q) or (V*A)/(V+A) being the value that the BCM sees. The other two can be neglected because your customer won't generally leave the switch in the "park" or "headlight" position for long.

Applying the general guideline above for widely differing resistors in parallel, without even doing any calculation you can tell that (V*Q)/(V+Q) is going to be pretty close to V. In practice it's so close that the BCM ignores the difference and activates the parking lights, just as you'd requested.

You can also tell with the general guideline, that (V*A)/(V+A) is going to be close to A - however it may also be close to H. In other words, when the aftermarket unit is requesting "parking lights" and the light switch is in the "auto" position, the BCM will either see it as a continued "auto" request, and do nothing unless the ignition's on, or it will see this as a "headlight" request and flash all the lights.

And that's why you want to interrupt the wire from the switch on a car with automatic headlights!


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C Renner's Auto Electronix
My service is cheap, quick, and good - pick any two

Chris,

I am actually an engineer so I understand what you are saying. I appreciate the electronics lesson though!

I actually got it working today, but it took some time to get it working correctly. My compustar brain has an integrated bypass (if you haven't used one, they're awesome) that communicates on the bus. It arms and disarms the factory alarm and thus flashes the turn signals with lock and unlock.

But with the parking lights hooked up through the relay, I was getting both parking and turn signals flashing with lock and unlock and the headlight switch in the off position. Turning it to auto would only flash the factory turn signals for some reason though. I can actually turn the factor turn signal flash on or off in the overhead computer but then the parking lights would only flash during lock/unlock with the switch off. Turning it to auto, I then got nothing. This bothered me.

On top of that, leaving it on auto and during remote start if I unlocked/locked the doors, the headlights would flash when the brain pulsed and thus unlatched the relay. This I really didn't like.

So I took a different approach. I used a negative trigger relay setup coming for the status line on the compustar. This then enabled on the parking lights during remote start and let's the BCM control the lock/unlock flash just like the OEM setup.

Works perfectly now. Too bad I didn't think of it sooners. I spent all day in the shop trying different things.

Anyhow, lesson learned. I just want to say thanks for all the help. Maybe it will help you also if you do a WJ in the future.