Hi beams

[Reatta90]

Hey guys, on my 90 Reatta, I just replaced the ignition lock cylinder. To do this I had to rent two different pullers from the auto parts store. I successfully replaced the cylinder and it was serving its purpose. After taking the tools back, I was driving the car a couple days after at night, and went to test my high beams, and noticed I could not turn them on. Every thing on the lever works including the turn signals (although, are a little tough to turn them on) the high beams can not be activated. I thought of just wiring in a toggle switch instead of taking every thing back out. But I also figured that if I could figure out what is actually being pushed inside the steering wheel to turn the turn signals on then I may be able to access it through the small cover over the multi function lever. Does anybody have any clue about this? 

[Ronnie]

The Hi/Lo switch in the steering column is just a momentary contact switch that sends a ground signal to the BCM telling it to dim or brighten the lights. Then the  BCM will send a signal to the Hi/Lo Beam relay. The wire going from the switch to the BCM on an '88-'89 model is a yellow wire with a black stripe. Not sure but I think it would be the same on a '90 model.

 

You can test the function of the switch by going into onboard diagnostics. Once the code display has completed, select BCM -->  BCM Inputs. Then scroll to Input B179 (Hi/Lo Beam Switch). Now turn the lights on. The status of B179 should read HI. Pull the dimmer lever and hold for a few seconds. The status should change to LO while you are holding the lever pulled back and go back to HI again when you release it. If that test is good replace the Hi/Lo relay. If the status stays HI all the time the BCM isn't getting a signal from the switch OR the switch isn't getting a good ground on the Black/white wire going to it. Hope this helps.

[Barney Eaton]

Another possibility is you have a damaged wire at the headlights.

The wires (LO,  HI, & Ground) go to the left (drivers headlight) and jumper to the passanger side.

IF someone has routed the wires incorrectly, it can break the connection inside the insulation and if that happens on the drivers side, both light will fail.

the attached photo shows how the wires should be routed (over the casting) 

if the wire to the headlight is coming up directly behind the bulb it is wrong.

You can take a pin and probe the cable ahead of the connection to see if current is there.

[Reatta90]

So theres a ground plate thst basically pulls down the signal, which enables the rest of the switchung circuit? Im trying to picture how the circuit is completed by the lever 

[Ronnie]

43 minutes ago, Reatta90 said:

Im trying to picture how the circuit is completed by the lever 

 

This should help.

 

 

[Reatta90]

So, electrically/electronically I understand how the function is, I mean I am curious about the physical connection, like what it physically looks like.