Dead car no one can figure out why?

Car- 2008 Honda accord lxp automatic transmission 43k miles warranty expired in Jan 2013

I had a breakdown in this car about a week ago I was driving about 20 MPH and all the sudden it sounded like something broke lose in my engine like a rock was bouncing around in there, then came a very loud buzzing sound. I parked the car and got out because it sounded like I had a branch or something stuck on my wheel. Nothing and then I hoped back in drove it very slowly and the buzzing was super loud and it was jerking then it just died. It would not start back up again.

The motor cranks, but will not turn over.

I had it towed to a automotive/transmission shop and they could not get power to the car I then towed it to another autoshop he had it for two days and ran every diagnostic he could and still could not get power to the car told me I would most likely need a new computer.

I then had it towed to Honda where it is currently at. They first said that it needed a new PCM because they could get no communication with the car. I ordered a new PCM and that costs $750 with everything.

They put in the new PCM and still the car will not work and they are not sure why? He said “every once in a while we get a car in here that kicks are ass and your car is it” Not exactly having a whole lot of confidence in this car?

Any guess on what this might be? Maybe something everyone has overlooked this far?
I have had it towed to 3 different shops and everyone is pretty much stumped. So I really cant afford to continue replacing things or guessing what should I do? Or what in the HELL is wrong with this car lol?


There are many possibilities; Having something sound like it was bouncing around in the engine tells me that you’ve snapped a belt or chain. Your car would crank, but not start. As far as a PCM…that was probably a guess by the dealer as to finding the problem, but not your solution. I would ask for a refund, plus your old PCM back. Have an independent person check your old PCM for failure.
Here’s a list where to start:

  1. Serpintine belt or timing chain
  2. Ignition/Spark/coils
  3. Fuel injectors/fuel pump.
  4. Ignition system, Honda “key” immobolizer.

Do not merely replace parts but inspect these areas for signs of broken or worn parts.

If the dealer can’t communicate to the PCM but it isn’t the PCM, I’d look into power and ground to that device. Besides a connection to the reader, it doesn’t need anything else to communicate. After you turn the key on, it should just start talking.
Sounds like they are taking a shotgun approach, kinda like aiming a shotgun at the car and replacing what gets hit.

This sounds like a broken timing belt/chain to me. Ask the mechanic to confirm/deny the integrity of the timing belt/chain before trying anything else.

When you say they can’t get power to the car, I’m not sure what this means. Do you mean they have figured out how to start it, but the engine won’t produce any power to make the car go? Or do you mean the car still won’t start, and their diagnostic computer is not able to communicate with the car’s computer (the PCM) to find out why? Or do you mean something else, like there is some circuit that isn’t being powered up by the car’s battery?

Given that it was replaced and that didn’t have any effect, I doubt – as mentioned above – there was anything wrong with your old PCM. Unless there was visible damage to it (broken traces), I’d ask them to reinstall the old one. PCM’s are usually quite reliable unless they’ve gotten so hot that the traces are damaged by thermal expansion (by the car being left out in hot sun), and PCM’s shouldn’t be replaced willy-nilly, for no good reason. That’s called “swap-tronics”, and it best avoided. The tech needs to find out what the problem is and work on that, not his primary diagnostic method to just swap stuff A new PCM introduces more problems than it solves.

I guess if I were in your situation, and the problem wasn’t the timing belt/chain, I’d cross my fingers, leave the car where it is, and hope the Honda dealership can fix it eventually. This is the kind of problem that often requires a dealership b/c they have Honda specific diagnostic tools. They may just need more time. Unless there is another Honda dealership nearby, give this problem to the dealership where the car is now, and ask them to fix it. They made the car right? So they should be able to fix it.

It may be that the techs there have spent very little time working on it, as they’ve had other customer’s cars to get finished first. Maybe they’ve only spent 1/2 hour so far, and they used that to replace the PCM. So once they get focussed on you car, hopefully they can get it fixed.

Car engines – after all – really aren’t that complicated. They really haven’t changed much since the early 1900’s. They work by a simple chain reaction. One cylinder fires, which causes the next cylinder to fire. And so on. If the engine has gas, compression, spark, correct ignition and valve timing, and all the parts are basically intact and freely rotate, it pretty much has to run. The dealership techs just need to test each of those one by one until they find out what is not working. Best of luck.

So are they able to communicate to this car or not? I thought you said they couldn’t.
If that thing isn’t communicating, a very basic very modern subsystem failed.

You need to clarify your statement that the car cranks, but won’t turn over.
You turn the key to “ON”, the dash lights up? All the “idiot” gauges?
Yes? Than you turn the key to start, and motor cranks? Yes?

As soon as they said the PCM was bad you should have run sorry to say. As others have already mentioned the lack of communication is due to a basic lack of power either to the PCM or the OBD2 diagnostic plug. It is hard to believe the dealer missed that basic point. There may be a bad fuse, relay, or wire connection causing that problem.

I assume the noises you heard were coming from the engine operation and if so be prepared for a major repair cost. I hope I’m wrong about that but going from the comments you made about the trouble it doesn’t sound good to me at all.

Thank you everyone for the helpful info.
Yes they cannot communicate with the car with there diagnostic tools even after the new install of the PCM.

Yes when they said no power they meant they can’t communicate with the PCM. Honda said after they put the new PCM in, the car will still not turn over or communicate. It has power like the windows, radio, miles on the car will come up and stuff, will crank, but will not turn over or communicate with anything like the diagnostic.
Honda did say that they brackets that were holding in the PCM were broken?
Thank you for the response

Honda bought the PCM and charged me for it, so wondering if my old one might still be good so I don’t have to pay for that.

And they did mention that they checked all the power up to the PCM and it was all good. I asked them what was taking so long and that took them all day to finally say that they needed to replace the PCM because he wanted to check everything else and make sure which I am hoping meant the power and the circuits?.

Sounds as if they are shotgunning the process. They need to check power to the ECM and that can be something as easy as a blown fuse or ignition switch.

You need to find out if they checked for power getting to the OBD-2 connector. This is the 16 pin connector they connect their scanner to in order to commuicate to the PCM. If power was getting to the PCM ok then that leaves about two possible problems for that trouble. One is power to the OBD-2 connector was missing for some reason or there is a fault with the data communication lines between those two points. Both of these things are simple to check out for trouble. I would guess there is at least a 97% chance that your original PCM is ok. Hopefuly they will fess up to their mistake.

Pins 16 and 4 are the power and ground pins on the OBD-2 connector. Since you have an '08 model it should be using CANbus communications on pins 6 and 14 for the comm link to the PCM.

Cougar - thank you for that info! I will definitely tell them to do that. I am hoping at this point I will be able to get that money back for the PCM.

You’re welcome for the help. I could very well be wrong about the PCM and the original was bad but since the replacement does the same thing it means something else is causing the communications trouble at least. The most likely senario is the power to the connector is missing and the data lines are okay.

The helpful wire data that @knfenimore provides shows what appears to be the PCM on the left side of the drawing and there are a couple of power lines to it. PIns A3 and A4 appear to be the data lines for the CAN bus communications from the PCM. It doesn’t show the OBD-2 connector but they will tie to it along with the power and ground I mentioned earlier.

This illustrates exactly what’s wrong with modern mechanics: the thing won’t communicate - let’s replace the thing that we communicate to and see what happens.
Most those guys are part swappers. Not diagnosticians.

Here is the Data Link connector

I bet your old computer was just fine. If they end up charging you for it, protest a lot because they made an unnecessary repair but also make sure you get the old part. You can probably sell it on ebay.
I guess it is in your dealer’s possession? If so, they are not going to check the wiring. They’ll replace it first.

@Remco thanks and yeah when I spoke with them I mentioned “well what about the noise that I heard before it broke down?” Could that be the computer? and I asked " doesn’t that sound like something broke?" He just keeps telling me that he need communicating from the car before they can identify anything. He did mention that the brackets holding in the PCM were broken and he also ordered new brackets. He said that the car has been in an accident in the front end and that was most likely what causes the broken/damaged bracket?

Yes the old PCM is there I have not seen or received any PCM yet.

I doubt an accident would have caused the PCM’s brackets to break. The PCM is not that heavy. Remember,Newton’s laws of motion (F=MA) from your high school physics class? A bunch of other things, heavier things - things with a lot more ‘M’ - would have broken first, before those brackets. Instead, maybe someone fooled with them installing an aftermarket radio.
Those brackets could serve as a ground connection, I guess. Not having a good ground could cause weird problems.

When mine did that, it took Goodyear about 30 minutes to diagnose a crank sensor. Yep, the noise sounds like timing or serpentine belt let loose and started wrecking things. I’d ask them to show you the diagnostic. Charts where it says to replace the PCM.

@RemcoW Whoaa your taking me back to Newton’s law well played sir!! Haha. Yeah thinking about it in that way that does not make since if those brackets were the only thing broken?? But as you said maybe someone messed with them and busted them in the process. Our car is totally stock tho now. We were I think the 3rd owner, but if there was a aftermarket stereo alarm etc. than they put all the original back on.