My car has close to 100k miles now, I don't hear a whine or anything when it goes out or comes on. And when it dies, it's immediate, like flipping a switch. Everthing goes black, and the gauges fall to zero instantly. I'll get another video on my way home from work of the gauges failing

 

My contribution is all the things I/ we tried on my car without success. What we did not do is further check the door modules, ECM and wiring to the IPC.
Grounds were checked and OK, BCM was replaced, 4 wire ground buss bar was removed, battery replaced, charging system checked out, and the OO had the IPC replaced. My windows never quit working, but the RDCM was failing and did not fully actuate the passenger side door lock. All else worked fine. Car had only 17K on it. Had I kept the car, I would have replaced it. No real problems other than IPC. As I said, Daddaro (God Rest his soul) spent a full day on it and could not find the culprit. Above and Beyond aka. Martin's Corvette, here in Summerville wanted to send the new(second) IPC off for dx and/ or repair and remove dash and track down every wire. I had run out of budget for it and traded it as is. Actually came out well $ -wise.
Hopefully, Bill, Lionel or others here who have tons of electrical success and expertise with the C5 will run this down with you. I will follow the process. I know how frustrating it can be, but then I am a bit short on the patience continuum.

Dave

 

So, I've been trying to catch it on video, but I've had no siccess. The harnesses in the doors seem fine, I'm starting to think it must be something with the IPC. Anyways, here are the codes I pulled they're all from history

58-SDM U1016 H Loss of comms PCM
U1040 H loss of comms TCS (ebcm specific)
U1096 H loss of comms IPC

80 radio no comms

A0-LDCM B2282 H battery 1 fault
B2286 H +5v reference fault
B2284 H battery 2 fault
U1064 H loss of comms with BCM
U1096 H loss of comms with IPC

A1-RDCM B2283 H battery 1 fault
B2285 H battery 2 fault
U1255 H serial data line malfunction
U1064 H loss of comms BCM
U1016 H loss of comms PCM
U1096 H loss of comms IPC

No more codes

 

The IPC has two battery power supplies. One is hot at all times and the other comes from a supply that is supplied by the ignition switch.

You are losing power.

1. The first place I would go is the Hot in Run Power from the switch. The Ignition switch is a well known problem area. There's a fuse for that. Then check the hot at all times fuse


2. FUSES. Fuses have been known to have bad spread fuse female terminals in the fuse box. Get a fuse spade pin and insert it into the fuse folder and see if the female holder is TIGH when you insert/withdraw the spade pin.

You can put a volt meter on each fuse and see if power goes away when the module fails. That's the easy way.

BC

 

Thanks Bill, I've discovered that if I push down on Fuse #13 that everything goes back to normal. I guess it must be a bad connection with the connector as you suggested.

 

:

I think you have the problem by the NUTS now!



Bill

 

Bill's suggestion was great. On mine , we checked all the fuses for continuity, but never the actual female connects. There is a good chance that was my problem. Fact that 13 is BCM seems even more compelling!. Great ending.

 

Well, I'm not going to call it a happy ending just yet. Still trying to figure out how to secure fuse 13 so I continue to get power to the IPC. And now I can't get the car to start, all fuses under the hood are fine. In the process of checking everything in the fuse panel. Just when I thought I was in the clear....

 

Well, alls well that ends well. Finally got it figured out, for some reason I had to replace fuse 37 as well. I was able to use needle nose pliars and a higher quality fuse for #13 which solved my problem. And thanks to reading some of Bills other posts, I was able to trouble shoot my clutch safety switch. It feels good to be back on the road with gauges that work. Fingers crossed, we'll see how long my problem is solved for. Thanks again for all the help

 

Interesting. 37 does show as a micro relay. What led you to it as a culprit? Do you believe that it caused the no-start condition? I am really curious , as I see others who have had our IPC problem without solving it, as I was unable to do. Any follow-up guidance can help others. And it might help us understand what we failed to look at on mine. I now believe that we should have pulled and checked the contact of each and every fuse. We did ascertain that none were blown, but failed to go the extra distance!
I am right with you in hoping you have a permanent fix to this vexing issue. Bill's lead to the fuses was right on!

 

Well... my trick worked for about a week, maybe two. I'm back at it trying to fix it again. Pretty much the same issue. Except now, it doesn't turn on or off while driving. It either works right away when I start the car, or not at all.
Car didn't want to start, so I did the purple to red jump and it fired right up. Multimeter shows power to all fuses around 13.8-14.0 with vehicle running. When I push on fuse 13 I can get the gauges to work. HOWEVER before, my light switch used to not have an effect. NOW when I put it in position 2, it displays the odometer. As if the car was turned off. Further more, when the car is running, and I hold down fuse 13. The gauges are reading the correct rpm, oil pressure, ect. But the DIC thinks the car is off. Like, I can check my stored fault codes while my car is running. So, I've come to basically 3 conclusions.
1) Bad ignition switch
2) Bad BCM
3) Bad interior fuse box? Why do the gauges work when I hold down the fuse?

I've cleaned grounds, they're all fine, removed the bus cap to the 4 wires next to BCM, shook the **** out of the door harness and checked connection, nothing seemed to do anything. I also disconnected the drivers seat and shook the wiring harness by the Trans and rear diff. Voltage to battery is 12.4 off and 14.35 running

 

If touching, pushing or looking crooked at fuse 13 changes how the car runs,,, shouldn't you figure out whats wrong with FUSE 13????

Most likely the prongs inside the fuse box are spread apart. Very common problem..

Until you get that problem solved, it could complicate the other symptoms.

BC

 

It could also be an internal bad solder in the fuse box where Fuse 13 contacts attach, but check first what Bill suggested. It's easier

 

So I pulled the passenger side fuse box out of place and tightened down everything in the back of the box. There are several red wires that go into 3 separate connectors on the back, I also wiggled fuse 9 and 13 and now everything is operating as it should. I checked DIC codes and all seems well.

I started looking at this thread
https://www.corvetteforum.com/forums...x-autopsy.html

Im thinking that ill get a new fuse box, swap it for my current one and then dissect my old one. Then I can see exactly what the problem looks like, so I can post it on here for everyone's reference, while still have a fully operational car.

 

Passanger fuse box removed from mount

 

So, it was an intermittent loss of power likely due to faulty connections in the fuse box, as Bill surmised. That is super information. As I said , we failed to find it on mine. Several others have been frustrated and not found it. So you are doing a great service to the C5 community.
Dave

 

I put in the new fuse box Friday morning, and everything is back to working. Im in the process of dismantling my old one right now. You can see through the hole for fuse 9 and 13 that the copper wire looks slightly different than all the other fuse holes. So it must have somehow gotten worn/bent/pushed and was causing intermittent power to my BCM. Id post pictures, but you cant see it nearly as well as you can in person. Anyways, just wanted to keep everyone up to date

 

Ive had some time now to disassemble my fuse box and have a look at everything. The second picture is of a fuse tap pin that was inserted into fuse slot #9 for the BCM. I imagine it was for an accessory to get power whenever the car is turned on. That pin was inserted too far and disrupted the brass wiring inside the fuse block itself, causing intermittent power to the BCM, and occasionally other fuses along the same track. Which is why when I pressed down on certain fuses I was able to achieve contact and get everything to work properly.
If you have a problem with fuse 9 your BCM is basically in "purgatory". I say this because the car thinks its being "cranked" but its actually not. Which is why the car will start when the clutch is depressed and the key is only in the "on" position. And the reason why certain accessories such as AC and radio worked but the windows and locks did not. Im sure someone else can elaborate more, but that's the best way I can think of describing it.

Anyways, for me, the fix was obviously a new fuse box. The my broken/original one was a massive pain to get apart. And if youre not careful you could actually make things worse. Since you can get a used one in working condition for $50-$75 with all the fuses still intact. Id recommend just buying one off a forum member, or vendor. Its nice to have all the extra fuses and switches anyways.
***Huge thank you to users Bill Curlee & David Shiel. Thank you guys again for all your help**

To remove your old fuse box, simply pull the neg terminal off your battery. Gain access to the fuse box in the passenger foot well unbolt the mount to the left hand side, unbolt the power cable on the most "northern" portion of the fuse box. Then carefully remove the 3 plugs and 3 bolts on the back of the fuse box and swap in the new in. It literally takes 10 minutes.

I think I covered everything. The pictures I took wouldn't upload properly, they kept getting blurry so I decided to use these instead just to illustrate what Im talking about

 

Again, these are not my pictures, theyre only for an example. Ill try to replace them in the future if my phone ever decides to cooperate


Here are the copper wires, mine was actually bent away from the fuse slot around #9



Here is a generic picture of a fuse tap. I WOULD NOT RECOMMEND using these . This is what caused the problem in the first place. Ive never used these before, and in fact the first time I saw it was when I was searching for the source of my issues. Use a mini fuse circuit tap instead.

 

I'm glad you were able to fix the problem and thank you for coming back with your findings