mux problem 2007 300c

Hey everyone, I am haveing some trouble with the mux system in a 2007 300c. After wiring in the two relays the provide 610 ohm and 180 ohms to the negitve acc and start I could only get the car to start by adding a diode to the 87a terminal with the stripe facing the relay. This in turn kept the the instument cluster from working, but if I took the diode out the car would start once and the the next try would not. I tried other  resistors on the acc. relay with no luck , moved my ground going into the relays to a new location, took starter kill out of the equation... It seems to work fine until I add the key side of the mux into the mix. My thought is that the resistsnce of the key side of the mux is the culprit but I was looking for some input on the subject. Thanks in advance for any help! Where ever there is a problem there is opportunity.

Did you use the reference wire off the factory harness for ground????  Make sure you have the right resistance....to check you have to cut the wire(which you have) and put your black lead on the ground reference wire and the red on the wire that was cut ignition side.  See what resistance it gives you when you put the car in acc and then on start.

what are you using to trigger the relays ? chek your resistance with a volt metter put one probe on the MUX key side and the other on an purple and orange wire the put the car on acc and see the readings wat ever it gives you thats your acc resistance now crank the car and see the resistance what ever it gives you thats your second starter resistanc. also follow this diagram http://documents.audiovox.com/700821.pdf and if your check engin light is one just disconnect the battery that would taje care of that any questions let me know.in the worst case I would recommend you an xk532

do you have to CUT the mux wire or can you tie into with 30? (Rather do that than do a 87a to 30 if possble)

To answer enice I used regular ground. Is the reference wire purple on this car? its the only one not used at this point. dtk1 has mentioned a bypass, but this customer only has one key so I cannot program any mods that I have looked up. Does anyone know of a mod that will program with one key and give me mux as well?Where ever there is a problem there is opportunity.

should have used a bypass that does the mux for you.

If the customer only has one key, how are you bypassing the immobilizer?

I have removed the transponder chip and attached to the antenna ring and hidden this unit.Where ever there is a problem there is opportunity.

What unit have you hidden? It sounds to me like the problem may be with the transponder, not the mux wire. If I were you I would advise the customer to go get a 2nd key programmed (it doesn't have to have the remote control, a regular grey headed key will work and cost approx. $75 from a dealer), and do a bypass the proper way.C Renner's Auto Electronix

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