Innocent Fool

Just bought a 1990 Pickup 4x4 and am trying to get it through inspection
Just about everything is done except the brake warning light won't go out. It got flagged for not turning on when you pull the e-brake so I took out the instrument panel and it looks like to last owner removed the bulb. Replaced the bulb and it just stays on. Disconnected the e-brake switch and it still stays on. Checked out the e-brake switch with a meter and it is OK. Manually pressed the switch to make sure the e-brake arm was hitting and it still stays on. Disconnected the connector to the master cyl under the hood that attaches to the float in the brake fluid cap. Light still stays on. Fluid in MC is good. Happens when the truck is running or not (Key On). Goes out when the key is off

The only thing I can think of is the PO grounded out the circuit when he installed the stereo or something

I'm almost thinking about wiring the switch direct to the bulb and insulating the bulb from the PCB on the back of the cluster but I don't know if I really want to do that...

Anyone have any ideas?

worshipmentor

iTrader: (3)

Hmmmm........
it makes me wonder if it doesnt have something to do with the section of the circuitry that causes the brake warning light to come on when there is an issue with the charging system. I found the plug on the back of my alternator was loose (DOH!) causing my light to be on. I'm not saying that is your problem but the diode in the circuit that causes the light to come on at that point might have something to do with it. If it were me I would pull the dash and start tracing out wiring traces to see where the brake warning light gets its ground.

justin_4runner

is there a pressure switch on the brake lines or some type of eletronic item that tells the system when there is not eought pressure and lights up on the dash, when i first get in my 4runner mine will be on tell i pump the brakes a couple times then it will go out. could also be part of the abs system if u have one, below is a link for some wire diagrams of the brake set up.

http://www.ncttora.com/fsm/1990-1995...stemci/abs.pdf


http://www.ncttora.com/fsm/1990-1995...ci/rearabs.pdf

Innocent Fool

Update

Swapped in another cluster and it does the same thing.
I think something from the C connector is feeding 12V to pin D-11 but can't find anything with the meter.

Haven't totally solved the issue yet but found if I disconnect the C-4 pin from the block connector on the back of the cluster I loose the charge light but the brake light works as normal. (edit: brake light does not light with engine off and key in run position but does turn on and off with the parking brake).

Checked the battery with the engine running and it is charging as normal (14.25v)

Here's the link to the cluster electrical diagram with some troubleshooting
http://personal.utulsa.edu/~nathan-b.../6combinat.pdf

scope103

The Green-White wire from the cluster (D11 in the diagram you provided, A11 in my 94, but that's probably just a naming change) only goes to two places; the green-white to the brake-level sensor, and the green-white to the parking brake switch. If you still have the cluster in your hand, disconnect both switches and the panel. If the green-white wire (from any end) has continuity to ground, that's your problem (each switch just grounds the wire, when the fluid level is LOW, and the parking brake is ON).

As you said, the PO could have nicked that wire to ground somewhere sometime. Finding that nick may be difficult, but since the replacement would only be two wires it wouldn't be a tough job to just run your own. (Finding green wire with a white stripe might be a trick ... Just kidding!)

Good luck.

Innocent Fool

Checked the green-white wire as suggested and it seems OK. I'm thinking if the green-white wire (d-11) was grounding out the light would still be lit with the C-block connector unplugged

Checked the connector in the back of the alt as suggested and it appears to be OK. No change. I would "think" that if this was an issue the charge light would also come on.

I checked out two separate clusters with a meter and it looks like D-11 connects to C-4 through a diode. Diode on both clusters measure the same and I know the one cluster is good. I pulled pin c-4 from the connector and lost the charge light but everything else seems to work. The brake light doesn't come on as part of the light test when starting the engine but other than that everything else seems to work. I figure I can live with that.

Kinda weird ....

MP's4R

Did you make sure the brake fluid was topped off. That'll trip the light too.

Innocent Fool

Checked the fluid and it is good.

MP's4R

My bad. Shoulda read closer.