Test tool i just bought

My BCM 1997 C5

Having a problem and I feel that my BCM is the problem. I can not open my hatch or turn on my fog lights with the switch mounted on the dash. I bought a switch and the same thing. I also can not open my fuel filler door by the switch. This test tool allows me to operate them from the plug and or thru the switch and or thru the fuse. #26 fuse is for the rear hatch and when I touch the fuse with the probe of tester it shows 00.0 but when I push the rocker switch forward the hatch will open. If I remember the fuse for the fog lights is #6 and the same thing. Does anyone have ideas or comments. I Welcome them all. I feel my BCM needs replaced. I have been talking with DINO'S Corvette Salvage and am waiting for his reply.

 

You can check the switch inputs before condemning the BCM. Check for voltage at each BCM input from the switch when you press the button. i'd have to open the schematics to figure out what to test, but there should be a live wire at the switch and then the other 2 wires should have power when the corresponding button is pressed. Check voltage at each wire on the switch and post back what you find.

 

I believe there are a total of 7 wires that are in this switch, but I will check. Thank you but I will say I wish I was more literate and not so illiterate when it comes to electrical problems but I am willing to try and yes try to learn

 

The foot well fuse block minifuse 32 feeds an orange wire to the switch. Pressing the fog light button will put power onto the orange/black wire. Pressing the rear hatch button will put power onto the black wire.

 

Last year I had problems with my foglight switch ( I thought) . My foglights would not go on when I press th fogswitch , only a short blink in the fogswitch indicator .
I found that the multifunction switch had several volts drop over it's internal contact set .
I measured the voltage in this big connector below the steeringwheel .
I measures just above 10 volt when I should have measures battery voltage.
My guess is that your multifunction switch is the cause of your problem but this you can verify with your multimeter .
After replacement of the switch everything has worked fine

 

Do not ask me how I posted those pictures before but right now I can not post anything.

Now checking the voltage with my new tester on the orange wire there is 0 none, but when I push the rocker button it shows 10.8, but yet my gas filler lid opens. Now checking the orange/black wire, it shows 0, both when I push the fog/hatch button Now when I check the black wire the same 0, both when I push the fog/hatch button but when I push the rocker switch on the tester it shows 13.0 and opens my hatch. now when I check the brown wire it shows 0, but when I push the rocker button on the tester it shows 12.4 and the dash lights come on and buzzer goes off telling you the lights are on.

I am really dumb founded, Everything worked until the last time I took our the dash gage cluster to change over to LED lights. Just all of a sudden when I put it back in there 3 items are not working. Now with all of my testing and unplugging the wires on the BCM now, I do not show any mileage numbers or anything in that window and all of my DIC buttons do nothing but yet all the lights are on. Right now I have the inside of the car in disarray and am not going to put back together till I get it fixed.

 

No power on the orange wire sounds like your hatch/fog button not working problem. Did you check the fuse?

Your cluster issue is likely either internally in the cluster or the serial communications. I believe the cluster would work fine without the BCM even installed.

Be careful injecting power into wires. Make sure you know the circuit and that it's OK to put power onto the circuit that way before doing so.

 

I bought another switch from DINO'S and it is the same will not operate anything. I am at the point now of I think I am going to have to get a BCM from Dino. I have power at the fuse but nothing at the switch and I am sure it all goes thru the BCM

 

I would suggest you verify/read voltages, as explained by Lionelhutz in the post below, before blindly buying more parts and report back.

At the switch, do you have:

• 12V in the orange wire always?
• 12V in the orange/black wire, while pressing the fog light button?
• 12V in the black wire, while pressing the rear hatch button?

You mentioned you "have power at the fuse, but nothing at the switch". As you can see in the first schematic below, Fuse 32 is directly connected to Pin 1 of the switch with an Orange wire. This wire doesn't go through the BCM. If Pin 1 is not always hot, you have to find where the link between Fuse 32 and Pin 1 is open.

Did you check for voltage both testing points on the upper edge of Fuse 32?

 

Your problem most likely has nothing to do with the BCM.

There is a problem between the fuse and the orange wire at the switch end. The voltage at the fuse is not reaching the orange wire at the switch connector.

You already proved the black wire is OK and that the BCM will open the hatch just fine.

Connect your tester probe to the orange/black wire with the running/parking lights on and inject voltage into it. Each time you do, the fogs should alternate on and off.

Any splices or repair work done to the wiring harnesses in your car?

 

I kneed to know what part of this [ switch or plug connector ] did you replace. Was it the BLACK parts and if so where did you get it or do you have a part no. for it. I found mine and the first orange wire you see and I had 12.7 volts, but connecting to the other orange wire, which is smaller than the other and the same size that goes to the switch in the dash I have 0 volts. Other wires I check, not all had voltage, but the one that did all showed 12.5 - 13.0 volts. Thank you for all your help.

 

@97Chuck69 Chuck, at the beginning you mentioned electrical troubleshooting was not one of your strengths. We can try to help you troubleshoot this, but only if you answer what we ask you

In Post 9 above, I asked these 3 simple questions. Could you please check that and report back?

At the switch, do you have:

• 12V in the orange wire always?
• 12V in the orange/black wire, while pressing the fog light button?
• 12V in the black wire, while pressing the rear hatch button?

 

OK I did what you said. I connected the tester to the BL/OR wire and put the run/park switch on and put power to it and YES the fog lights came on/off. AND to the best of my knowledge there has not been any kind of repair to the wires harness. Also can you tell me what CKT means. A lot of times I this with numbers after it but can not find anything out in the manuals. Also I found this in the repair manual for the fog lights and according to this it does go thru the BCM or maybe at least to it. BUT D4 is a blank port. Nothing there. Like I have said before that the fog lights, rear hatch, and the filler cap all worked up to the point I had removed the gage cluster the last time to check out why I had a dash light not working. I have found no broken wires, no cut wires so far. I am so sorry for being a pain in the A but this electrical stuff is not my fortay but I do want to learn and can not afford to pay some one to do it because as you know electrical work is nothing but all time and that is expensive. THANK YOU for all the help and I am not giving up. OH I HAVE POWER AT THE LOWER SIDE OF #32 BUT NOTHIING AT THE TOP, IT WAS 13.0

From the 1997 Corvette repair manual

From the 1997 Corvette repair manual

 

SORRY pencil in the wrong place. Should be at D4 NOT D5

 

I show no power at the ORANGE WIRE
I show no power at the or/bl wire,while pressing the fog light button
I show no power at the bl wire, while pressing the rear hatch button

I show power at the #32 fuse at the bottom, 13.0 v, and nothing at the top

And I am sorry I thought I answered this but no problem

 

@97Chuck69 No you did not do what I asked ... You kept doing what you wanted to do!

EDIT: I just saw you answered my 3 questions while I was typing this reply

You are kind of dangerous with that tester of yours . Do you have a "plain" multimeter to just take voltage readings? I asked you to take 3 voltage measurements, but the last 2 were "dependants" of the first one: if there is no voltage in the orange wire connected to Pin 1 of the switch, then there can't be voltage in the orange/black or in the black wires either when the switch buttons are pushed.

I just wanted to double-check that because you never explicitly established the lack of voltage in the orange wire connected to Pin 1 of the switch.

As I mentioned in Post 9 above, it seemed (and now was indirectly verified) that power from Fuse 32 is not reaching Pin 1 of the switch, that's why neither your foglights nor your rear hatch are working. On the other hand, by checking that both, your foglights and rear hatch, work when you inject power directly to the orange/black and to the black wires respectively, you verified that your BCM is most probably fine.

Your problem is the lack of voltage in Pin 1 of the switch.


I'm glad I asked you to verify if both testing points on the upper edge of Fuse 32 had power, even though your Post 8 above was giving that fuse a passing grade. Having power in just one testing point means the fuse is blown/bad and that should be the cause of your problems. Replace fuse and retest.


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CKT means "circuit". For example your problem is affecting Circuit 2840 that has an Orange wire with a cross sectional area of .5 mm² equivalent to 20 gauge (see annotations in schematic above).


The Orange wire goes from IP Fuseblock's "Pin F12 - Connector C1" to Foglight Switch's "Pin 1".

The Orange/Black wire goes from Foglight Switch's "Pin 2" to BCM's "Pin D4 - Connector C2".

(See annotations in schematic above).

 

GCG - I asked him to do that test you quoted.

97Chuck69 - That test proved the BCM is fine. Both the ORG/BLK and BLK wires you have tested go to the BCM as inputs and then the BCM triggers the fog lights and truck release as outputs. So, you have proved the BCM is fine because it's doing what it's should be doing. The orange power wire to the switch does not pass through the BCM so that wire not having power is not caused by the BCM. From the wiring diagrams, it appears that wire come directly from the fuse block to the switch without passing through any other connectors on the way.

What you wrote about the fuse was a little cryptic. On fuse 32, you measured battery voltage on one side but 0V on the other side? If you answer yes, then the fuse is blown. Next thing to do is install a good fuse and ensure that there is battery voltage when measured on both sides of the fuse. If you are unclear what measuring on both sides of the fuse means, there are little opening in the front facing side of the fuse (the side facing out of the fuse block) where you can put a meter probe so it contacts the metal inside the fuse so you can measure the voltage of the fuse. This does not mean remove the fuse and measure the contacts the fuse plugs into.

I think CKT means circuit, or at least that's a close enough interpretation.

 

I know. I explicitly mentioned you by name, and the quotation also has your name on it. Click here to take a look.

I tried to make Chuck understand the importance of following a process when troubleshooting, otherwise it's just craziness . I analyzed the results of the tests performed and gave him a diagnosis and solution, along with some miscellaneous help he requested, above in Post 16.

 

No, the quote at the top of post 16 is the one I'm talking about. I posted to do the fog light test so he wasn't just randomly doing testing.

 

Lionelhutz & GCG, I used a multimeter this morning and it showed the same as my other tester 0V. I have been in and around this thing so many time and so frustrated too, and all the help you guys have given me is phenomenal. And as I said at the beginning I wish I was more electrical literate. Well I must tell you that in all of my stupidity yes I found the problem and yes it was a blown fuse. I swear I did check #32 and found it good, at least I thought I checked it. Changed it and all is working good. I must apologize for running you through all this really needlessly. Yes I need to not get so frustrated, and slow down, in things like this but I hate electrical problem's. AGAIN I AM SO SORRY.. CHUCK