2017 Touring V6
Problem history:
1. Noticed the ability to roll down windows and open moonroof with either the key fob or key itself is gone. Note, all other functions of the key works such as door lock/unlock, remote start, etc.
2. Moonroof auto functions are gone. Have repeatedly went through the reset procedure to no avail.
3. Moonroof can be opened and closed with the overhead switch but the moonroof doesn't stop automatically. When it moves to full open, it will start clicking. Same in the close direction.
I took it into the local dealer for diagnosis. Their response follows with the order of shot gunning parts:
1. The moonroof control unit is not taking the learn procedure, the system is not responding to the commands. Recommend replacing the unit for $1374.
2. Replace driver door latch assembly. $436.
3. Replace the MICU. $883.
So we are talking a possible ~$2700 with no guarantees. If they would tell me which one would actually fix these problems, I would go ahead and get it done. I am wondering if anyone has insight as to which solution would actually work.
Thanks......

 

Right now those three components are just guesses. With the prices you are getting quoted, you should find a shop to quoate a more thorough electrical diagnosis. These control units communicate on two network wires, so first would be using an oscilloscope on the network wires to check the network communication electrically. One bad component can take down the MICU network, so various items can go wrong. It is worth the cost of diagnosis vs the costs you listed above on guesses on the real problem.

 

Thanks for the response. Unfortunately, I cannot find an independent shop that has access to the schematics or the proprietary equipment necessary to troubleshoot the problems.

 

The equipment isn't really proprietary for Hondas, it would just be specialized for auto electronics diagnostics. Shops that do diagnostic work should subscribe to alldata and would have enough informaiton to troubleshoot. Since Orlando is a farily large city, you should be able to find a shop that can do that type of work. You'll pay for the diagnostic time, but could waste ~$1400 on a moonroof control unit that might not be broken based on a guess.

I don't want to assume anything, so are you planning to do any diagnostic work yourself?

 

I am an experienced troubleshooter with a BSEE, 6 years as an ETR in the USN, as well as a Professional Engineer in control systems and would like to, but without access to wiring diagrams and control descriptions it would probably be futile.

2017 Accord 3.5 V6 Touring AT

 

The moonroof control unit should have two heavier gauge wires for power and ground to run the motor. The other thinner wires would either be from the moonroof switch or the network wire(s). The network wires could be twisted pair or it could be just one wire.

If it was two wires, the signals are opposite and would have a 5V difference. So on a scope of each network wire, the voltage lines should be mirror images with square wave packets. Pinehollow diagnostics on youtube is a good channel to see this kind of testing.

A wiring diagram would be helpful. I think you can get a one month subscription to alldata for ~$20 for your car. It is worth a shot if you think you can do the tests. This isn't an urgent repair as you can still drive the car.

 

Thanks, I appreciate the information. Which of the original 3 items are coded to the VIN of the vehicle that would require a programmer?
2017 Accord 3.5 V6 Touring AT

 

For coding to the VIN, I have no idea. You would have to look at the shop manual for the installation procedure to see if a Honda HDS or scanner is required. I'll guess the moonroof requires a calibration and not really registering, but would still require a decent scanner.

Another thought is to unplug the moonroof control unit/motor connector to see if some of the other functions return. This could give you some information about the system components in question from the dealership.

Modern cars are frustrating for diagnostics because of the digital communication between control units and how the control unit is a black box that actually sends power/ground to the component. It is hard to figure out the root cause(s).