Guys back in July I posted a thread concerning my gauge cluster not working. Everything else in the car works as it should. The seatbelt light and all other lights in the cluster work on start up, just no gauges and the HUD shows two dashes. I have replaced fuses 19 and 25 in the passenger floorboard, even though both appeared to be fine. I replaced the battery yesterday with a new one thinking it was because the old battery didn't have enough power as I believed was the case back in July. I then charged the new battery fully. The gauges worked fine until yesterday, now no matter if the battery is fully charged or not the gauges will not work and no DIC working. I am prepared to remove the cluster and send it to be rebuilt unless someone here has some ideas I should attempt first. If I do have to remove the cluster and send it off, any suggestions on a reputable company that someone has experience with that can rebuild the unit? Thank you in advance for your help.

 

I forgot to mention it is 2004 convertible, automatic.

 

I would use the service manual's procedure to troubleshoot before I went to the trouble of removing the IPC. It would suck to go to all that trouble only to find out your problem lies elsewhere.

 

You stated that you check the fuses but,, Did you actually break out a meter and see if you had proper voltage at the fuse/s? There are TWO test points on top of every fuse in your fuse box. Use the meter to test both test points to ground.
You 'SHOULD" see full battery voltage on both fuse test points. Make sure that the key is ON when testing.

If you have proper voltage, the next test would be to test the grounds.

Use the internal DTC reading routine to read ALL DTCs. Post up what you have.

Seeing that you have activity on the IPC, I would suspect that you are not getting proper serial data to the cluster. That comes from the sensors through the BCM. I would also check all FOUR BCM fuses for proper voltage and to see if they are corroded, or damaged.

The BCM can also get damaged from moisture/water. If the circuit board inside the big silver box gets corroded, it can do some very very strange stuff to other modules.
TRY THIS: Find the two STAR connectors in the passengers foot well to he left of the BCM between the carpet and the tunnel wall.. There are two. Remove the top shorting top off the connector with four wires. That isolates the LDCM, RDCM & Seat Control Module from the rest of the modules. Do that and see if you regain data on the ICP.

Let us know what you find.

BC

 

Bill if I understand you correctly there are two star fasteners to the left of the BCM and I need to "Remove the top shorting top off the connector with four wires." I don't know what that means, can you clarify please? I greatly appreciate your help with this, Thank you very much. The DIC will not work, along with the entire gauge cluster, I can connect an OBD II code reader and see what codes, if any are present and I will post them once I get them, but it will be tomorrow before I can do that, I have two jobs and only get one afternoon off a week.

 

Dads thank you for your help and the manual you provided, I am reading up on the troubleshooting now.

 

Guys I just got home and I disconnected the star connector near the bcm and nothing changed. I still have no gauges, dic, or backlighting in the IPC with headlights on. Once I plugged the star connector back in everything else works as it should except the ipc. With the star connector unplugged my windows stopped working, I don't know if that should happen so I mention it. I connected an obd 2 code reader but there were no codes present and no pending codes.

 

Unless you have a REALLY FANCY OBD2 Reader, It will not usually see the chassis or body specific DTCs. You need DO NOT need anything to read your DTCs except your fingers and the buttons to the right of the IPC. There are numerous sights on the web that take you through the steps to read the DTCs through the cars system using the IPC routine.


How to Access C5 Corvette Diagnostic Codes (motortrend.com)

 

My instrument cluster and dic do not work, that's the problem I am having

 

Did you read the voltage on the IPC Fuse (ignition ON) ?? You should see full battery voltage on the two test points on top of the fuse to a chassis ground..

BC

 

Not yet, I have to get a multimeter to check it. I hope to have one by Friday. I have read about every post you have ever written on multiple forums and I am thankful for your knowledge and willingness to help. I will post my findings on Friday once I get a multimeter
. Thank you very much for your help.

 

I just tested fuses19 and 25 in the passenger floorboard and they are both showing 12.17 volts with the key in the on position

 

Well,,,, If you have power to the IPC, the only other thing that is required for it to function is GROUND. That would be the next check step.
To do that, you would have to remove the IPC and get to the connector and measure the ground pin in the connector to a known good chassis ground point.

IF you determine that you have good power and ground, the module it self is the next suspect. While its out, I would disassemble the IPC and inspect the main board for broken / loose / cold solder joints. Pretty easy to do. Let me know what you think.

BC

 

Bill thank you. I actually have another ipc that a buddy of mine had laying around. I will take mine out this weekend and plug the other one up and see if it works, at least that is my plan. I will update.

 

Bill do you think cleaning g104 under the battery tray could make a difference?

 

Bill what should I see when measuring the ground?

 

Possibly the ignition switch. My understanding is these switch contacts go bad and can cause instrument cluster problems.

 

Grounds are usually checked using an OHM Meter on a deenergized circuit. You would connect one lead of the meter to the chassis ground point (preferably where that circuit grounds to)) and the other lead to the ground wire inside the connector. You ideally should see zero ohms but because of wire lengths and other electrical things, seeing a tenth or two ohms isn't out of the realm of normal readings. If you see OHMS of resistance, that wire, ground point is compromised

If you have a truly defective / poor ground, you can use a dc voltmeter on a low volt scale and measure from connector ground wire to chassis ground. Any voltage reading would indicate a compromised ground path. Theoretically, You should see ZERO VOLTS on a properly grounded component / circuit. The lower the voltage read, the better. The goal is ZERO VOLTS DC.

Lets talk about voltage and CURRENT in a circuit. If a component, wire, switch, connection is bad/defective, many times, you will see good/adequate "NO LOAD" VOLTAGE. When you place a LOAD on a circuit, the bad connection will act as a resistance/resistor and not flow the proper current to power the load. When you load the circuit; say with a good incandescent lamp, you will see circuit voltage drop (due to the bad connection) and the current in the circuit will be LOW. (That incandescent lamp will light dimly)
So, in conclusion, If you want to see if a circuit is adequate to support proper component operation, you need to test it under LOAD .

Ignition switch contacts will pit, corrode, carbon up. When they do that, the circuits that the bad contacts inside the switch can output Another way and probably the more common way an Ignition Switch can fail is the TWO Connectors that plug into the switch can have BAD,SPREAD,BURNT Female connections. The female connections inside the connector spread apart and make poor contact with the male pins inside the switch. That would be the very first thing that I would investigate.

Bill

 

If you find someone to fix it let me know because I tried and could not. I drove two hours into another state gave it to them only to get a call two weeks later and they said they coul'd'nt fix it.

 

I am sorry for this very late update.

I pulled both battery cables off the battery, and found a light coating of corrosion on the cables and battery post. Cleaned everything, installed a new battery, (since I had already bought it), and now the car works perfectly. All new vehicles are very sensitive to voltage flucuations.

Steve