The park brake dashboard light glows dimly when the right front wheel rotates to certain positions. The abs sensor, fluid level sensor and brake activation sensor have been eliminated as possible causes. I know of no other electrical sensors on the wheel or circuit. The right front wheel rotation doesn't do this. The wheel turns the drive shaft which must activate something in the transmission. I think there must be a short circuit somewhere between a transmission activated circuit (speedometer?) and the park brake circuit. I'm trying to find a wiring diagram to see if this is possible, and figure out where the short circuit might be. Thanks for reading this far. :) Any ideas?
The short could be any where that has a circuit to the dash as the bulbs will carry the short to other areas of the dash , this is noted by the speedo wire you've already found and not related to brake circuit ,try disconnecting the brake light switch from foot and parking brake that will eliminate that circuit or confirm it
Testimonial: "Hi Steve, Thank you for your reply. I did disconnect the park brake activation switch and the fluid level sensor cables. The light still comes on dimly when the speedometer sensor is in the closed position. Disconnecting the speedometer sensor cable stops the light coming on. I've inspected the various junction plugs behind the dash and tried moving the wiring loom about to see whether that stops the short, but it doesn't. Am beginning to wonder whether the short is in the dashboard unit?"
try removing the other bulbs one by one and if light goes off then what ever that bulb was for could well be the circuit , cheaper than new panel and might not cure the pro, electrical faults are a nightmare but the bulb thing is something i've seen first hand find the problem , worth a go
Thanks Steve, It is getting clear that I have to get in behind the instrument panel. Not sure how to get in there but concerted effort will likely reveal.
was there actually a short circuit?
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Public library, automotive database,(i like mitchell) check service bulletins and recalls, check wiring updates under dealer info... now pull up the schematic and parouse the info you may have found. compare it to the changes and updates that may be available.
This can be timely and effective approach short of asking a tech at the toyota service dept. BUT, giving them a chance to answer may reveal another course.
I dont need to tell you there are so many questions that come up when searching for electrical answers...what equipment and options, type of emission category, what powertrain etc. (I.E.) go check the car and come back to the schematic to continue...
another idea, does it have pad wear sensors and are you taking away a ground thats being provided by the sensor when you go upline in the circuit to disconnect? you could check the plug you disconnected for a ground, the try to trace it to the wheel. or get any pad related sensor away from the pad. excuse me for not having brake job experience on this model so its just a brainstorm idea.
another idea, with all known wireplugs disconnected, is the harness in continuity with chassis ground?
i once had motor coaches that did this, and they ended up recalling switches that indicated brake pressure during application. the light illuminated when it wanted to and seemed to be affected by turning at a slow roll. we found that by working in the area of the steering column and saw a drip coming from the sensor switch. turned out it was vibration and temperature that was making the intermittant ground come and go, not turning and rolling so much.
Bonzai !
Testimonial: "Thank you Dan. Helpful suggestions. It has been a mission trying to isolate the cause. This model does not have pad wear sensors as far as I can tell. The pads are OK. The speedometer sensor in closed position is the circuit providing current to make the park brake/fluid level sensor light glow even when the other sensors cables are disconnected. I don't know how to test whether "the harness is in continuity with the chassis ground". I can move the car into the speedometer sensor activation position and leave the car stationary and park brake light continues to glow. That is how I've been testing for the circuits that deactivate it."
get the harness diagram onto some sheets of paper. determine the components connected to the light. unplug all of them. put ohmmeter on 200 ohm scale. put one lead on the wire and one lead on a chassis component known to be in continuity with B- or body ground strap
if the light illuminates when the sensor is in trip or closed position, that means the side of the sensor that comes into play during trip must contain the path to ground. this fact may eliminate most of the schematic from your view and help you follow the remaining portion to the component or the next test
lets reitterate what the concern is to avoid confusion. this is the parking brake indicator light. or, the red brake light. the one that comes on if the reservoir was low lets say. it comes on dimly? or normal steady on? or it blinks in relationship to the turning of the right front drive axle. it stops doing it when you unplug the vehicle speed sensor connector. you think a ground is being produced at the connection every time the sensor trips or closes the circuit. i would point out that the VSS has several jobs in the car. its mV signal is used by the instruments, the trans, the additional systems like traction control or brake override..etc. now when? always? when the keys on? when the engines running? as long as you turn the axle. now do you see why the library and tsb info is so important? everyone who reads this can accidentally misinformed. the dealer may shy away because they cant test it over the phone. If there is already some doings by toyota/lexus on this concern, you need to find out. i saw some concerns related to brake light support brace. you dont want to confuse speed readers. there also may be a guided pinpoint test in the toyo/lex service manuals for this specific condition. lemme kno?
dimly lit. i reread your starting request. thats like chafed or damaged circuits in contact. or, fluid entry into a sensor. or, water entry into connection.. you may want a clean set of tests to what it has for an abs module a pcm and or a bcm or tcm and get pass codes noted. it may set a memory code and not turn on a light, or vice versa. inspect the modules in their locations and look for anything unusual. ..i have seen mice chewing wires or water leak into the passenger compartment. even evaporator drain water getting in and the resulting water vapor affecting systems. wet seat control boxes doing strange electrical anomalies. modules bolted down uneven.... whatever. so back to what i had said previously. if the harness tests bad for cont. to gnd. follow it.. but do the research for tsb's please
Dan you are really helpful. :-) I'm guessing there is a leak across the speed sensor circuit to the park brake light circuit. It only glows dimly when the wheel is in a certain position. It glows less dimly (almost invisible when the car is going any speed. Only visible when travelly really slow. I've inspected all the electrical plugs and tried moving the wire bundles about in case am able to alter a short between wires. No luck with that. I'm thinking the short could be in the instrument panel but again this is an uninformed guess. The car has been doing this for the last 8 years, but only now has it been cited as an safety warrant issue.
thought of another way those speed sensors can cause annomalies. if they have shavings or chips built up on them. I.E. in a rear brake (rabs) ford i have seen screwy pump motor operation and heightened sensitivity to actuate an "abs" stop
so if the coil and magnet inside are affected in your sensor by some kind of failure or non failure code annomaly could it generate enough EMI to induce into another wire....y'kno where you were checkin wire looms? what if u used a shielding material to cover the harness for the light, thereby blocking induction? crazy, crazy for blinkin so dimlyyyy
waiting to see if you did your manufacturer research and checked all the ways it can be found in an automotive database
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I found these two links, maybe there's something in there.
http://www.apexi-usa.com/manuals/electronics/neo_diagram.pdf
http://alflash.com.ua/RX/1MZ-FE_Engine_Control_SystemRX300_99.pdf
Testimonial: "Hi Sixpack6t9, Thanks for the links. Interesting detail and close to what I'm after but couldn't find a wiring diagram for my model Windom."
theres a good chance research from the library may reveal toyota has done some work in this area. since they like to gather data rather than publish, noone but the dealers know. you can access published TSBs at the library or report your vin and concern to the dealer service dept. they have engineering data sometimes on a broadcast technicians message thats still in flux looking for where they get tech feedback. they may already know what to do
Thanks. I spoke to a Toyota dealer today. He was helpful but didn't know. He did say it sounded like a short and could be caused by water. He said there was no guarrantee they'd find it quickly. That is why I need the wiring diagrams. Will check out the library.
electromagnetic induction. a neighboring circuit with "noise" induces its flux onto the circuit in question. if mice arent chewing it and the harness is not chafed. moisture entry into a component or connector is not found, shielding may be the answer. are any other cars reporting this symptom? like to the NHTSA? they have a site where they can be petitioned. they are the last word on whether the car maker has to take action, or whether they can wait and fix them their own way, or what. i was thinking, if the instrument cluster is an electronic type, you could send it out to the appropriate support vendor through the dealer. but they probably need to know what action to take. if you do that research we talked about or make those calls. it may shortcut it for you.
Hi Dan, I've paused before removing the instrument cluster. Keeping an eye out for a cheap second hand one to replace it with, at least for tests. It is such an annoying fault because it doesn't affect the vehicle operation but will take it off the road. :(
soooooo? what did toyota say? or lexus or whomever. is this annomaly something being reported by a number of owners? or is it just that one car? and did the sensor in the transmission show any signs of misshapen where the sensorcoil is inside the cyllindrical portion? did it have a "noisy" signal? i gots ta kno, i gots ta kno
did you ever do the research suggested to eliminate manufacturer info? did the tests ever get run and data recorded? other folks come along after and read what DID fix it
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SOURCE: I need a 1996 Toyota Windom 2MZ FE engine wiring diagram please?
Hello! The only way to acquire a complete set of wiring diagrams is to purchase a repair manual or at your local library...Unless your only interested in a certain circuit...If the latter is the case tell me which circuit...Guru...saailer
I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867
Testimonial: "Thanks a lot. An e-mail has been sent to the given address from [email protected]. Waiting for your kind reply."
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The problem is resolved when the speedometer sensor wire is disconnected, SO THE QUESTION IS NOW to identify where these two circuits intersect. :)
with all related connectors to components disconnected, check ohms to gnd. at the harness. no short? it has to be one of the components. plug them back in one by one till the short shows up.
if the short is intermittant, you have to reassemble and re create it. if the sensor you are disconnecting is permeated by fluid, it may partially short when it reaches necessary temperature to produce the dim brake light illumination.
Hi Dan, I will try the short tests tomorrow. The short is not intermittent. What if the problem is in the dashboard instrument panel? If say the pulse coming through the speedometer sensor is grounding via the instrument panel. How would I test that?
hmm. terminology. vehicle speed sensor, VSS produces a mV signal when its field is tripped by the passing toothed reluctor wheel attached to the axle or hub its mounted in proximity of. to me, this pinpoint test should be first because the sensor must do what it does to have all the systems use its signal. i recommend obtaining a toyo/lex service manual and following the engineers predetermined steps to say its "ok" and it receives and sends correctly to wires which have on them what the engineer thinks they have. when you get readings and compare them to the test, you can decide. i should mention i have seen sensors that (even though they had no visible damage) were causing the processor to set the warning lamp. sensor "noise" or harsh erratic oscillation can be seen on an oscilloscope. the new kind of scan tools that replaced the small hand held ones often have an LCD oscilloscpe in them. they can record and playback data. If you want fast answers. you could take the pin point test to a shop that can read this for you. the other tests start with a code reading. since all of these types of tests are indicators for the technician, I would get the info he's privy to so i could evaluate.
i have also seen other sensors that were giving the processor fits but there was no code set, and no mil lamp(malfunction indicator lamp) the resulting actions taken by the processor were not predicted in the testing literature we had... so... we had to improvise. even to the point where borrowing parts off a car that was not having that problem. we could then take comparitive readings off that cars wires to compare to the problem car. engineers could be consulted over the phone but just for specific data and instruction. nothing was faster than making sure the wires were ok, then trying another part.
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