why is this diode here?

 

Are the wires comming from your power seats or your ride control it's hard to tell? I'm sure it's there for some reason?

 

its not the seats or the ride control, it looks like is snakes along side the center consel and goes down and back

 

What is your reason for concern? You don't mention "issues" with the car. Do you have a FSM? Before I'd be concerned I'd need to be having issues with the car that I could troubleshoot to the harness and connector involved!

 

What year 'vette? Maybe someone with an FSM for that year can look it
up for you.

Kettering's law: Parts you don't put on car cost nothing to make, nothing
to install, and never break. That diode is there for a reason.


Chuck

 

i have an fsm and im tracing what it could be, but with out knowing what this connector is for or where it goes im in the dark.

1993 corvette

 

There are diodes all over the car. The C4 shares systems and has to share grounds where ever they are available. Diodes just prevent one system from powering up another thru the other side of the circuit. Because Everything is ground controlled, its cheap protection. With all the "always hot" wires there are lots of ways for power to find a path to something.
The opt 68 a/c uses one in the comp clutch to protect the BCM from feeding power back thru the single wire circuit...basically the BCM has to fail in order for their to be a need for the diode to protect anything,...what has already failed. Some GM engineer is justifying his salary...thats all.

 

it doesn't look factory to me, it was covered in duct tape and a crappy solder job. does anyone else have the same diode as i do? does anyone know what is connector is for?

 

I have the same on my 94 vetted also covered with black duct tape also did not look oem but have been having trouble with power seats not working and battery drainage. Turn out circuit breaker was over heating because diode was damaged causing battery drainage. The wires it's attached to run from circuit breaker to power seat switches and there is only one diode on my drivers side none on passenger side. That's all i know. I think it has something to do with power all ways going to seats even with ignition off.

 

Diodes have 2 functions, limit the amount of current that can flow through them and limit the direction it can flow through them.

 

When you create a magnetic field in a motor, relay, or compressor clutch and then shut off that device, the collapsing magnetic field creates a current in the opposite polarity. Diodes are used to shunt that current to prevent damage to whatever is driving the device. You'll find them in several places on your C4.

 

Post #11, and someone finally gets it!! The GM engineers aren't so stupid that they'll throw a diode into the wiring just to frustrate the amateurs.

Here's a diagram to try to explain it:



When an inductive component ( relay, solenoid or motor) is active, current flows thru the component. When the switch (or electronics) opens in order to stop the current flow and turn off the component, the inductance of the component will force current to continue flowing because of the collapsing magnetic field in the component. If you have a diode in parallel with the component (like my diagram), the current caused by the collapsing magnetic field will flow thru the diode, rather than causing a spike in voltage at the switch. That spike in voltage will cause a spark in the switch, which shortens the life of the switch. The diode is there to lengthen the life of the switch. (Good engineering!)

You can do your own experiment if you want to see proof for yourself! With 12 v. battery and a solenoid, but rather than using a switch, touch the two wires together to actuate the solenoid. Watch for a spark as you move the two wires apart, as if you're opening a switch. You MUST use two wires that you can touch together in order to see the spark, not a switch! Now put a power diode (1N4001 or equiv.) in parallel to the solenoid (like my diagram), and repeat your test. Hmmmm . . . no spark!

 

If this diode were damaged would it render lumbar inoperable? I’ve been chasing non working lumbar for awhile, but haven't pulled carpet yet.
My power seats work, both lumbar switches have continuity, and the lumbar pumps are in working condition. However, no power at the orange power wire coming out of the carpet. Wonder if this is related?

 

Fantastic info, thank you! Years ago I remember the car being jumped accidentally reverse polarity, bet that is it. Time to year down the center stack and investigate further

 

If it is a kickback diode as explained by Hot Rod above probably not. Usually when diodes fail they fail open. In that case the circuit will will still function but there will be a voltage spike every time you used the motor. That voltage spike could damage the switch, the motor or transistors in another circuit but it would continue to function until it did one of those things. It is possible there would be other indications including a shock when you let go of the switch or radio noise.

In the unlikely event the diode failed closed you would probably blow a fuse if you tried to actuate the circuit. In that case it would not work

 

My diagram is correct. I'm sorry that you're one of those people who are confused. You need to understand my text in order to understand my diagram.

Auburn2 gets it.

 

You are arguing over semantics. Electrons flow from negative to positive, current flows from positive to negative those two things are facts which no amount of debate can change.

A traditional PN diode is forward biased when there are holes on the anode and electrons on the cathode and it will conduct DC in such a state. A traditional PN diode is reversed biased when there are holes on the cathode and electrons on the anode and will not conduct DC in such a state.

The diagram above shows the proper arrangement of a kickback diode and the correct flow of electrons in such a circuit. The diode clamps the DC voltage to whatever the forward bias breakdown voltage is when the switch is opened (0.7 volts for most diodes) and current momentarily flows through the diode which is now forward biased in the opposite direction of flow through the coil. There is no short because the control switch is open and there is no path to the positive battery terminal, the only flow is "around" the coil and kickback diode.

If the arrows are taken to mean current flow and not electron flow they are backwards but the diagram and the circuit itself is still correct.

 

Thanks for the feedback, makes sense. I’d assume it fails open as well, but deep down I want this diode to be the root of my problem

It’s strange, everything in the car works except the lumbar and it’s due to no power at the connector coming through the carpet (2 wires - orange/black). There’s no separate fuse for lumbar as it runs through the 6-way power seats and those work just fine.

Suppose it could be a ground issue but admittedly I havnt probed further than the connector at the carpet. This diode caught my attention because that’s where power for the lumbar runs according to the FSM (down the side of the console).

 

It is unlikely it is a ground issue if they are all grounded together and the rest of the seat motors are working. if it is a simple DC motor for the lumbar suppport, you can hotwire it to the battery and see if it works.

 

How do we know the lumbar pumps are in working condition? post 13