04 jeep grand cherokee parking lights

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! 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.