Midnightwreck
New member
Hello all,
I thought I would write a quick post for those who may have had a similar symptom, in hopes to spare you the anguish I just went through. first of all, I replaced the OEM radio in my '06 Montana about 3 to 4 years ago. Everything went well at first. I got he interface module to simulate the Data Bus communications and restore the warning chimes. The aftermarket radio was a mid to low end JVC unit. Perfect for my listening needs.
Anyway, the last couple of years has seen some erratic electrical behaviour in the van. Dead batteries with the van parked overnight, flickering lights, the occasional "charging system malfunction" message, etc. I cut off and replaced the batter post clamps with new brass ones, and went to start the van. It wouldn't start. No lights on the instrument cluster, and no chimes. All the wires were restored to like-new condition, so the problem was NOT with the clamps and connections. It turns out, that as I was trying to get a nut back onto the grounding post of the passenger side fender panel, I must have fried the interface module for the radio. I concluded this when I tried pulling all of the fuses out one by one for a visual inspection. With the doors open and key in the ignition, all of a sudden I seen the instrument cluster was illuminated, as normal. I tried starting the van for the fun of it, and it started like there was nothing ever wrong. Put the fuse back in, and it wouldn't start again. Pulled the fuse, and the van was working fine.
Conclusion: With the aftermarket interface module suspected blown, it caused interference with the many data busses that General Motors uses, like the MOST and GMLAN - Low speed buss. When checking out symptoms on a website, of what happens when aftermarket devices are plugged into the data links, I found the following can occur; radio stays on after car is turned off, buss or LAN traffic stays active which leads to battery drain, the inability to program or reprogram control modules because of interference or by not allowing the buss to power down, preventing On-Star from sending diagnostic data, engine and transmission performance issues with the Check engine MIL light on, reduced power and DIC messages, intermittent stalling, transmission not shifting for one key cycle (TCM in default mode), instrument cluster gauges erratic or flickering, and loss of communication with Engine Control Module (Error U0100).
I had two of the above symptoms. Dead battery and erratic or flickering instrument cluster/gauges.
I removed the suspect interface module and radio, and reinstalled the OEM radio that came with the van, and everything works fine.
Thanks. Hope this helps someone.
~wreck.
I thought I would write a quick post for those who may have had a similar symptom, in hopes to spare you the anguish I just went through. first of all, I replaced the OEM radio in my '06 Montana about 3 to 4 years ago. Everything went well at first. I got he interface module to simulate the Data Bus communications and restore the warning chimes. The aftermarket radio was a mid to low end JVC unit. Perfect for my listening needs.
Anyway, the last couple of years has seen some erratic electrical behaviour in the van. Dead batteries with the van parked overnight, flickering lights, the occasional "charging system malfunction" message, etc. I cut off and replaced the batter post clamps with new brass ones, and went to start the van. It wouldn't start. No lights on the instrument cluster, and no chimes. All the wires were restored to like-new condition, so the problem was NOT with the clamps and connections. It turns out, that as I was trying to get a nut back onto the grounding post of the passenger side fender panel, I must have fried the interface module for the radio. I concluded this when I tried pulling all of the fuses out one by one for a visual inspection. With the doors open and key in the ignition, all of a sudden I seen the instrument cluster was illuminated, as normal. I tried starting the van for the fun of it, and it started like there was nothing ever wrong. Put the fuse back in, and it wouldn't start again. Pulled the fuse, and the van was working fine.
Conclusion: With the aftermarket interface module suspected blown, it caused interference with the many data busses that General Motors uses, like the MOST and GMLAN - Low speed buss. When checking out symptoms on a website, of what happens when aftermarket devices are plugged into the data links, I found the following can occur; radio stays on after car is turned off, buss or LAN traffic stays active which leads to battery drain, the inability to program or reprogram control modules because of interference or by not allowing the buss to power down, preventing On-Star from sending diagnostic data, engine and transmission performance issues with the Check engine MIL light on, reduced power and DIC messages, intermittent stalling, transmission not shifting for one key cycle (TCM in default mode), instrument cluster gauges erratic or flickering, and loss of communication with Engine Control Module (Error U0100).
I had two of the above symptoms. Dead battery and erratic or flickering instrument cluster/gauges.
I removed the suspect interface module and radio, and reinstalled the OEM radio that came with the van, and everything works fine.
Thanks. Hope this helps someone.
~wreck.
