: E 90 Code - VCC Brake Switch Signal Problem



EldoRedo91
12-11-10, 01:24 PM
Folks:

I have had an E 90 code (VCC Brake Switch Signal Problem) pop up several times in the past month or so on my 91 ETC. The Service Manual is not a lot of help in terms of discussing the issue -- specifically, is this something serious? I had the transmission rebuilt about three years ago and I have not noticed any problems at all with its operation. If this is a sign of a real problem with the switch, would I notice it? It is an expensive issue to deal with? Any input would be appreciated!

the recluse
12-11-10, 08:44 PM
Folks:

I have had an E 90 code (VCC Brake Switch Signal Problem) pop up several times in the past month or so on my 91 ETC. The Service Manual is not a lot of help in terms of discussing the issue -- specifically, is this something serious? I had the transmission rebuilt about three years ago and I have not noticed any problems at all with its operation. If this is a sign of a real problem with the switch, would I notice it? It is an expensive issue to deal with? Any input would be appreciated!

Not expensive at all. If you look under the dash, right above the brake pedal, you'll see a wiring harness that connects to a momentary push button switch. That's the switch that's bad. When the switch goes out, you'll have no brake lights which can lead to someone possibly rear-ending you.

$10 at the parts store.

carnut
12-12-10, 11:11 AM
Could be as simple as the brake light switch misadjusted. Put your foot under the pedal and lift up. If you hear a click or ratchet noise, you have now readjusted the switch. Erase the code and drive it. Application of the brakes disengages the VCC above approx. 40 MPH. if the switch is misadjusted or faulty or the wires to it are loose you will get a intermittant code. The brake lights should turn on with just a slight application of the pedal.

EldoRedo
05-09-11, 10:47 PM
Folks:

Bumping this in search of more information as I am still regularly getting the E90 code. I appreciate the above replies, but I am concerned this is more of a problem than just a switch -- and I am now somewhat doubtful it's the brake light switch above the brake pedal. It is true, however, that I have had to adjust the position of the brake switch in the bracket above the pedal to cure a problem with the brake lights not going out (!).

It's hard to find a definitive answer on the Web -- although I have found the following information:

The purpose of the TCC (torque clutch converter) is "to eliminate slippage in the torque converter, which in turn, improves fuel economy during cruise. This also reduces the heat produced within the torque converter, thuse extending the life of the transmission fluid."

"The VCC [Viscous Clutch Converter] clutch [found in post 86-Cadillacs] works the same way, except that it does not provide a 100 percent lockup between the engine and the transmission input shaft...When the VCC is applied, it allows about 20 RPM slippage at 60 MPH, just enough to eliminate some of the torsional vibration between the engine and the transmission. The viscous clutch lockup is controlled the same way as a TCC clutch, except that transmission fluid temperature plays a larger role in its control."

Another auto forum post advised:

"To check VCC you should drive at some constant 50 mph and with your right foot on gas pedal touch the brake pedal with your left foot slightly to engage the brake switch. Watch RPM on DIC it should jump some 100-200 rpm. If it happens your VCC works properly."

I did this and did not notice an RPM change.

So I'm thinking that this may be is a problem with a switch/solenoid inside the transmission? As I originally mentioned, the car seems to operate and drive fine; yet I hate to just keep clearing the code and pretending it's not a problem.

Any additional thoughts?

Thanks!

drewsdeville
05-09-11, 11:02 PM
There's a simple way to determine if the vcc solenoid is engaging:

Enter onboard dianostics
View ECM DATA
On the climate control display, watch for the rear defroster symbol to light up. If it lights, the vcc is engaging. If it doesn't light, it's not engaging.

EldoRedo
05-10-11, 09:19 AM
Thanks -- I ran that test and the defroster symbol did not light -- which obviously seems to confirm the original code. But my questions are still:

1. Is this critical to get fixed? and
2. Sounds like it means opening up the transmission ($$)?

ehall
05-10-11, 09:55 AM
Your fuel mileage at higher speeds will suffer until it's fixed. It's probably a simple thing like a broken switch or a loose wire that will take longer to locate than to repair.

carnut
05-10-11, 10:46 AM
This test mentioned above must be done as you drive the car. I presume you did this.

Sevillian273
05-10-11, 11:28 AM
E039 should set rather quickly if the VCC does not physically engage.

EldoRedo
05-11-11, 09:01 AM
DOH! I was so used to pulling codes while parked I didn't realize I needed to be moving to run the test drewsdeville suggested. I have now done so and the defroster symbol did not light up. On the other hand, I also did not get an E039 code. Thanks for all the help -- I'll try to get this resolved when I next visit my mechanic.

drewsdeville
05-11-11, 09:19 AM
To elaborate further, the VCC won't engage until cruising at or above 40 mph or so. Therefore, be sure to take it on a good cruise while checking.

carnut
05-11-11, 10:55 AM
I agree. Road speed and trans fluid up to temperature are required for the circuit to be complete.

Sevillian273
05-11-11, 12:08 PM
Engine must be in closed loop also. (>160deg)

I installed a switch between the ECM and the solenoid on the ground lead. This way I can disable the VCC when I want. When the switch is off, I always get E039. I've never seen an E090 though.

EldoRedo
05-11-11, 10:12 PM
OK I will check this during morning commute tomorrow. Thanks.

Update: ran this test this morning after about 30 minutes of driving above 60 MPH -- did NOT see the defroster light. Based on the comments, it seems like this is something that I might want to get fixed -- but is not critical. Thanks so much to all who replied.