I’m in desperate need of assistance. I recently installed a Kenwood DDX-9904S head unit in my 2015 Tundra, utilizing the iDatalink Maestro RR and harnesses to retain factory features like the GPS antenna and USB port. Initially, everything seemed to work flawlessly. The sound was great, CarPlay was functioning perfectly, and all vehicle information, including TPMS, was displaying correctly. However, I encountered a problem: the head unit would sometimes remain powered on even after the truck was turned off.
Following advice from Crutchfield, I disconnected the OBD2 connector wire, as they suggested it wasn’t necessary for my vehicle. This indeed resolved the issue of the radio staying on. The radio now turned off with the truck, seemingly perfect.
Alt text: Kenwood DDX-9904S aftermarket car stereo head unit displaying a colorful interface.
However, disconnecting the OBD2 link had a downside. I lost all vehicle information display on the head unit, including crucial data like tire pressure monitoring (TPMS). Despite this, other functions like steering wheel controls, the USB connector, and CarPlay continued to work without issue.
Undeterred, I proceeded with the physical installation. I assembled the dash kit, carefully tucked all the wiring back into the dash cavity, and dry-fitted the radio into the dash. Before fully bolting everything in, I decided to do one final test.
This is when things went horribly wrong. The truck and all interior lights flickered and shuddered. The head unit began to cycle on and off repeatedly and then died completely. Worse still, the truck now refuses to start. Instead of the engine turning over, I’m met with a strange electrical groaning noise. A persistent clicking sound emanates from behind the dash, continuing even after the key is removed from the ignition. The instrument cluster remains dimly lit, and the headlights, despite indicating as ‘on’ on the dash, do not illuminate. This bizarre state persists for about 15-20 seconds, followed by a relay click, the dome lights returning to full brightness, and the system reverting to a state resembling just after turning off the truck normally, before opening the door.
Alt text: Generic car dashboard interior view highlighting the space where a car head unit is typically installed.
In a frantic attempt to diagnose the problem, I checked every fuse I could locate – on the radio itself, on the wiring harness, and in both fuse boxes of the truck. None were blown. The Kenwood head unit remains unresponsive, leaving me unsure if it has been damaged. The situation is clearly more than just a radio issue, as even after completely removing the aftermarket components and reinstalling the stock head unit, the truck still exhibits the same no-start condition, clicking noises, and lack of power to the original head unit.
Alt text: iDatalink Maestro RR module, a car audio integration device, shown on a white background.
The iDatalink Maestro unit itself seems to be functioning, as I was able to connect it to my PC and successfully re-flash it. This suggests the Maestro module may have survived whatever electrical event occurred.
I am completely stumped and desperately seeking any insight into what might have caused this issue and, more importantly, how to fix it. There are no burnt plastic smells, and I’m out of ideas. My truck is currently an immobile paperweight in my garage, and any help would be greatly appreciated!
