Diagnostic help needed!!!

[Silver Bullet]

Hi all,

First post and a big ask from a new member, sorry about that.

Car is at the dealers currently and I get the impression they are struggling a bit.

Background - 2005 MN6 Z51, DD, been mine approx 4 months and 10k miles. Fitted a new battery 3 months ago (Optima Yellow) and also fitted a rebuilt transmission from RPM 2 months ago. No other issues.

3 days ago I backed into the garage as usual, hit the "off" button and still got the "shift to reverse" message. Ensured it was physically still in (it was) and decided I'd need to disconnect the battery to prevent it flattening. Next day hooked it up and it now will not start. Check engine light on, lots of juice in battery but nothing, starter solenoid clicks.

Things I have checked. Both reverse signal switches are good, continuity forward to engine harness good, all fuses/relays I can access good. Tried jumping, still same symptoms.

So it went to the dealer yesterday and I have just had the call for more diag time needed as they are stumped. They have pulled codes....

B0005
B1480
B2530
B1325
U1000
U1153
U1088
U1040

He started trying to blame the transmission because it is none standard with two reverse switches which is utter BS. I feel I should pull the car from them but I am utterly stuck without it and have nowhere else to go.

Please help if you can and I promise my next post will be more positive!

Ritch.

[LLC5]

Originally Posted by Silver Bullet

Hi all,

First post and a big ask from a new member, sorry about that.

Car is at the dealers currently and I get the impression they are struggling a bit.

Background - 2005 MN6 Z51, DD, been mine approx 4 months and 10k miles. Fitted a new battery 3 months ago (Optima Yellow) and also fitted a rebuilt transmission from RPM 2 months ago. No other issues.

3 days ago I backed into the garage as usual, hit the "off" button and still got the "shift to reverse" message. Ensured it was physically still in (it was) and decided I'd need to disconnect the battery to prevent it flattening. Next day hooked it up and it now will not start. Check engine light on, lots of juice in battery but nothing, starter solenoid clicks.

Things I have checked. Both reverse signal switches are good, continuity forward to engine harness good, all fuses/relays I can access good. Tried jumping, still same symptoms.

So it went to the dealer yesterday and I have just had the call for more diag time needed as they are stumped. They have pulled codes....

B0005
B1480
B2530
B1325
U1000
U1153
U1088
U1040

He started trying to blame the transmission because it is none standard with two reverse switches which is utter BS. I feel I should pull the car from them but I am utterly stuck without it and have nowhere else to go.

Please help if you can and I promise my next post will be more positive!

Ritch.

The first place to start in this situtation is to properly load test the battery with a carbon pile load tester to verify that the battery is good and that it is the proper size and rating for the vehicle. Low voltage caused by bad/weak/improper battery's can cause all sorts of problems with these vehicles. If the battery positively tests good after the load test then you can move on from there, but don't go any farther until the battery is confirmed good, and don't ASSume anything :). Good luck with it.

[c4c5specialist]

HI there,

First, what does NONE STANDARD MEAN????

2 Reverse switches are critical to how the shut off system works and column lock functions.

Now, that being said, the DTC here are confusing.

B0005 is for an AUTOMATIC park switch input, but you said it was a manual transmission

B1480 is for battery rundown protection
B1325 is for a voltage being above/below specification

The communications codes are for a Class 2 data link failure, this is NOT for the GMLAN networks, which controls on and off function and starting of the vehicle.

That being said, my guess is that there is a wiring issue creating the concern.

NOTHING here correlates to your issue EXCEPT for the B0005 which is actually for an automatic equipped car.

Is there more details that are available???

Allthebest, c4c5

[Silver Bullet]

Thanks LLC, the battery is 3 months old and is AFAIK the correct version specified for the car. It has performed flawlessly since fitting but I definately hear what you are saying. The Tech asked how old the battery was so hopefully he will have tried a "known good" one. It's on my list of Questions.

C4/5 - I was hoping you would get involved here as I have read lots of stuff you have posted in my time lurking!

The tech never got back to me yesterday despite asking for authority to do 2 more hours of diag - this was at 3pm. I am expecting a call some point this morning.

I will endeavour to get more information from him when he calls as to which modules set which codes, anything else I should ask?

To answer your question ref the transmission. I installed an exchange rebuilt transmission to the vehicle to correct a grinding 2nd gear. I supplied the VIN and the transmission was supplied exactly matching the one I had. My 2005 HELM manual CLEARLY shows 2 x reverse sense switches and the pinout of C184 (IIRC) as having two independent back up lamp/reverse connections. I am aware this transmission is utterly totally normal! :D

The Chevvy "Corvette specialist" and by association his technician did NOT know this. He spent a substantial amount of time on the phone telling me how it was "non standard" to have the two switches and someone must have added the second hole in the tranny! Quite a concern tbh. I shall be pulling the car from them this morning if I don't get any further joy. I have remained perfectly polite throughout this and my offer of taking the manual up to the dealers and showing him was met with some embarresment on his behalf.


I have been a hobbyist DIYer for decades now and try to do as much wrenching/repairing as I possibly can. It pained me seeing my pride and joy been towed away but I resigned myself to having to pay for the specialists. To now find myself in the hands of these muppets is really getting to me TBH.

So a question to you all - if I accept this car is going nowhere for some time and I invest in a second hand tech 2 is this something (with your help and experience) that I can sort out? I can't face authorising another 300 bucks of diag to be told my standard car is non standard!!!! I have the time and energy to do it I just don't know whether I am being unrealistic?

Time to get my head back in the DTC section of the Helm! Thankyou all for your time helping me.

Ritch.

[Silver Bullet]

Just thought of something else as well.

The reverse lamps aren't working but were before? I had assumed that the logic in the bcm that wasn't detecting the reverse signal was also not energising the lamps.

I have checked both switches and also the continuity forward to the engine harness, I got a little lost as to where the signal then went following this.

The manual makes a fascinating read for a tech geek like myself! Just wish I could work this fault myself, it's my kind of thing!

[LLC5]

Originally Posted by Silver Bullet

Just thought of something else as well.

The reverse lamps aren't working but were before? I had assumed that the logic in the bcm that wasn't detecting the reverse signal was also not energising the lamps.

I have checked both switches and also the continuity forward to the engine harness, I got a little lost as to where the signal then went following this.

The manual makes a fascinating read for a tech geek like myself! Just wish I could work this fault myself, it's my kind of thing!

Paul (c4c5) will take over from here.

To help him it would be a good idea to detail when and why the transmission was replaced, how long everything worked properly after the RPM transmission install, what work (if any) was done after the transmission install. When was the last time everything worked properly on this vehicle, and were all your lights including the backup's working before and after the transmission install? Good luck with it.

[Silver Bullet]

Originally Posted by LLC5

Paul (c4c5) will take over from here.

To help him it would be a good idea to detail when and why the transmission was replaced, how long everything worked properly after the RPM transmission install, what work (if any) was done after the transmission install. When was the last time everything worked properly on this vehicle, and were all your lights including the backup's working before and after the transmission install? Good luck with it.

OK cool,

I don't want to give any misconceptions but I think the transmission is unrelated. I think the dealer has seen the B0005 code and the replaced tranny and began to join dots. His lack of knowledge of how many switches caused me concern, that's why I made the comment.

However I understand there seems a link so here is the full bio!!!

Car purchased by me May/Jun this year. It had just over 60k, clean carfax, 2 owners, everything checked out but has a slight grind on 1st/2nd when changing down. I am a reasonably capable (and modest :D) DIYer so thought I would take it on as it was a good price and great nick. 2 owners, 6 years and 60k does not signify a particularly inherent problem car to me. It is an "out of the factory" MN6, fully documented. Everything checks out.

2 months in I have satisfied myself it is most likely internal transmission so stripped right back to the clutch. Replaced entire clutch assembly whist in there and the new (rebuilt) transmission was on the way. It is identical unit to the one I had, matched by VIN and original SS, TFT, Reverse switches etc swapped over. This is all approximately 4k miles since. Car is a DD and I commute mainly highway 45 miles each way 6 days out of 9.

The car has behaved perfectly since then, when I have had a little leave it has sat over a week and fired into life first time without issue. I do not beat on the car at all.

The day it failed it drove the journey home with no problems at all. Reversed into garage as usual, press the off switch and it turns off as usual but chimes and "switch to reverse" is diplayed. Story taken up then in post #1.

Now I "think" somewhere in my memory it is possible the reverse lamps did not light the night before when I parked up? The Air force has a great habit of getting me into work at all hours of the night so I know they normally work but iirc I "think" I may have made a mental note that for some reason they didn't illuminate when backing into the slot that prior night.

So possibly to aid the fault finding the back up lamp circuit "may" have been inop the day before the "switch to reverse" message came up?

I can find only one other instance of this documented on the web by an owner and his fault was cured by a BCM replacement. I really hoped I'd grown out of random component swapping and was wanting to have a more functional analysis approach though.

For clarity I have been under the car and measured the continuity of both switches whilst my extremely understanding wife shifted between R And N. A nice healthy buzz in R and quiet in N. Oh how I wish the switches were knackered! I almost wish it was internal transmission as it's under warranty and a bit of graft would sort it! However, I'm in the lions den now and my air force wallet is cringing!!! :D

Guys, sorry for the long post and thanks again for your time.

[LLC5]

So this problem happened all at once backing into your garage, with no other prior symptoms?

Do your back up lights function when arming and disarming your alarm?

What did your battery load test at?

[Silver Bullet]

So this problem happened all at once backing into your garage, with no other prior symptoms

Yes. (Although it is "possible" the reverse lamps failed the day or 2 prior?"

Do your back up lights function when arming and disarming your alarm?
Good question, I don't think they ever have TBH. I have passive locking/arming enabled and I don't recall ever seeing the BU lamps lit at this time? They do normally work in the normal fashion though.

What did your battery load test at?
Still waiting for the dealership to get back to me. Yesterday at 3PM they asked for 2 hours diag authority which I agreed to. They have not made contact since. I am currently working another night shift so won't get to speak to them until tomorrow.

Cheers,
Ritch.

[Silver Bullet]

Sorry, another post for clarity, having re-read my posting I may have confused.

The car is a standard MN6 and the new transmission is a direct standard replacement.

The dealer was calling it "none standard" and the reason he cited was because of the 2 reverse switches where there should be 1! I had to educate him as to the standard fit on the 2005 MN6 with this reverse shut down feature.

I know it sounds ridiculous but it is true. I pointed him to the page in the manual where he should look. This is why I have nil faith.