cleaning 96 and 97 LX450 and land cruiser steering wheel for intermittent horn (2 Viewers)

[jonheld]

what's this one please?
"Do you get a good constant ground at pin 1 of the relay socket with the horn switch pressed?"

Continuity test between pin 1 of the relay socket and ground when the horn switch in the steering wheel is pressed.
You want to see close to 0 ohms or very low resistance.

NOTE: hearing a relay click is not a valid diagnostic. All that means is that the contactor is pulling in, but the internal contact points could be faulty. That is why I suggested testing/replacing the relay as a first step.
I'm not saying that the horn switch contacts can't be a problem, but you'd have to be using your horn an awful lot to wear them out.

This entre circuit contains A power source, a switch, a relay, and a load. The switch is in the steering wheel, the relay is in your hand, and the load is the horn.
By jumping pins 2-3 and confirming that the horn honks, you have eliminated 75% of the circuit. We know the power source is good, and all paths to the load, as well as the load are intact.
All that's left is to verify a good solid ground on the relay logic path when the horn switch is pressed. If all of that checks out then the issue must be with the relay or the contacts in the relay socket. There are no other possibilities. The laws of physics cannot be ignored.

 

[landcruiser3DP]

Continuity test between pin 1 of the relay socket and ground when the horn switch in the steering wheel is pressed.
You want to see close to 0 ohms or very low resistance.

NOTE: hearing a relay click is not a valid diagnostic. All that means is that the contactor is pulling in, but the internal contact points could be faulty. That is why I suggested testing/replacing the relay as a first step.
I'm not saying that the horn switch contacts can't be a problem, but you'd have to be using your horn an awful lot to wear them out.

This entre circuit contains A power source, a switch, a relay, and a load. The switch is in the steering wheel, the relay is in your hand, and the load is the horn.
By jumping pins 2-3 and confirming that the horn honks, you have eliminated 75% of the circuit. We know the power source is good, and all paths to the load, as well as the load are intact.
All that's left is to verify a good solid ground on the relay logic path when the horn switch is pressed. If all of that checks out then the issue must be with the relay or the contacts in the relay socket. There are no other possibilities. The laws of physics cannot be ignored.

OK. thanks a ton gents. also thanks to Jon here. i'm a little slow with the elektrikery but i've been at it for while so bear with me please. also apologies as it took me some time to get back to this.
i bench tested the horns. they both sound when i apply 12V. i cleaned the contacts at the horns. the connector at the horns is a bit tricky to clean since i couldn't figure out how to disassemble it so i did the best i could.
i may have to clean those again.
i bench tested the relay which afaik with a 3 pin relay is to simply energize the two spades and attach a test light. the test light lights up.
in the vehicle the relay makes a sound every time i push the horn.
additionally i was able to test each of the 1-3 tests Jon was kind enough to supply me with:
1. jump pin 2 and 3.
> horn sounds clearly.
2. do you get a constant 12+ at pin 2 of the relay circuit.
> this is POS lead into pin 2 and NEG lead to battery and dial to DC V and the answer is yes, 12+ volts.
3. do you get a good constant ground at pin 1 of the relay with the horn pressed?
> this is NEG probe into pin 1 and POS alligator clip to POS pole and hang the multimeter on the hood. i see 12+ volts at all four corners of the horn at all times without fail.

this is a little confusing since the horn will sound maybe 1 out of 20 or 30 times now whereas it was sounding regularly, then about half the time after replacing the clock spring.

anyway i need to reread Jon and other answers here but i guess i am going to spend $80 or whatever on a toyota relay or buy a cheap one at oriellys or something for $20.

i am also going to try to find a ground for this circuit at the DS kick panel i think.

then i am going to put back my "newly contacts cleaned" original steering wheel.

then i am going to try to clean the contacts in the harness at the horn again.

i'm all ears if i am missing something and i am obviously motivated to fix this.

 

[jonheld]

3. do you get a good constant ground at pin 1 of the relay with the horn pressed?
> this is NEG probe into pin 1 and POS alligator clip to POS pole and hang the multimeter on the hood. i see 12+ volts at all four corners of the horn at all times without fail.

You're not paying attention. Ground is not +12.
Look at the schematic in the EWD. The relay coil is energized by a hard ground on PIN 1 when the horn switch in the steering wheel is pressed.
REMOVE THE RELAY FROM THE CIRCUIT.
Set your meter to continuity (OHMS).
Stick a meter probe into relay socket pin 1.
Stick the other probe to the negative battery terminal.
Push the horn switch on the steering wheel.

You should see very low resistance, close to 0 ohms.

Remember that you have already verified 75% of the circuit by simply jumping pins 2-3. If the horn blows, then the power source is good, the horns are good, all connections to the horns are good. Move on. Stop testing items that you already verified. Get yourself out of the loop.

 

[landcruiser3DP]

You're not paying attention. Ground is not +12.
Look at the schematic in the EWD. The relay coil is energized by a hard ground on PIN 1 when the horn switch in the steering wheel is pressed.
REMOVE THE RELAY FROM THE CIRCUIT.
Set your meter to continuity (OHMS).
Stick a meter probe into relay socket pin 1.
Stick the other probe to the negative battery terminal.
Push the horn switch on the steering wheel.

You should see very low resistance, close to 0 ohms.

Remember that you have already verified 75% of the circuit by simply jumping pins 2-3. If the horn blows, then the power source is good, the horns are good, all connections to the horns are good. Move on. Stop testing items that you already verified. Get yourself out of the loop.

View attachment 2915301

hi jon.

thank you.

reading electrical diagrams is not really something i am able to do very easily. so i can only understand them to the extent they are explained. same with using a MM diagnostically. i can only do this if it is explained in a practice manner.
and actually i find each of them confusing enough i can't do the two at the same time.

i am sure this is true for a lot of otherwise very nice people.

for the #3 test you want MM set to Ohms and POS probe in slot 1 in the fuse box and NEG probe clipped to ground at the battery?

then you want to see if there is any resistance when i push the contacts closed at the steering wheel?

what is this testing please?

what should i expect to see when the horn is not pressed? OL meaning rhere is no circuit?

then when pressed you want to see 0 Ohm resistance? this means the circuit is good?

and if i see some kind of higher resistance i know i have some kind of bad ground or bad wire?

also, what am i testing when i do #3 set to DC V? aren't i testing if the horn is sending 12V from the 4 sets of contacts? i mean if i see 0 Volts for #3 when the horn is pressed and 12 V when it is pressed isn't this telling me that the circuit is good from the horn?

 

[jonheld]

You're chasing your tail here.
Again, by shorting pins 2-3 on the relay socket and hearing the horn blow, you have verified the power source (+12), you have verified ALL WIRING AND CONNECTORS through to the horns, as well as the horns themselves. There's NOTHING ELSE in this circuit left to verify except ground on pin 1 with the horn switch pressed.

With the meter in continuity setting, it makes no difference which probe goes where. You're looking for continuity between PIN 1 of the relay socket and ground. Ground is the NEGATIVE BATTERY TERMINAL.
Continuity means a short or 0 ohms. A reading of "OL" means an open circuit. You will see this with the meter in continuity with the leads not touching anything. If you touch the 2 leads together you should see a reading of 0 ohms, as there is now continuity between the 2. This is all explained in the manual that came with your meter and there are tutorials online on how to use one properly.

continuity : noun
the unbroken and consistent existence or operation of something over a period of time.

resistance : noun
the degree to which a substance or device opposes the passage of an electric current (ohms)

 

[landcruiser3DP]

You're chasing your tail here.
Again, by shorting pins 2-3 on the relay socket and hearing the horn blow, you have verified the power source (+12), you have verified ALL WIRING AND CONNECTORS through to the horns, as well as the horns themselves. There's NOTHING ELSE in this circuit left to verify except ground on pin 1 with the horn switch pressed.

With the meter in continuity setting, it makes no difference which probe goes where. You're looking for continuity between PIN 1 of the relay socket and ground. Ground is the NEGATIVE BATTERY TERMINAL.
Continuity means a short or 0 ohms. A reading of "OL" means an open circuit. You will see this with the meter in continuity with the leads not touching anything. If you touch the 2 leads together you should see a reading of 0 ohms, as there is now continuity between the 2. This is all explained in the manual that came with your meter and there are tutorials online on how to use one properly.

continuity : noun
the unbroken and consistent existence or operation of something over a period of time.

resistance : noun
the degree to which a substance or device opposes the passage of an electric current (ohms)

so just to ask again:

for the #3 test you want MM set to Ohms and one probe in slot 1 in the fuse box and the other probe clipped to ground at the battery? or you want the other probe clipped to the POS pole?

 

[jht3]

No. Ground. Black.

 

[landcruiser3DP]

No. Ground. Black.

lol. it's like some kind of jailhouse game of charades or pictionary getting straight answers with this low voltage stuff.
like this?

 

[landcruiser3DP]

also.

No. Ground. Black.

also. i have a hard time reading these things. how do i know whether pin 1, 2 or 3 are hot or ground? or is that how i should think about them as being hot side or ground side?
i should "read" the diagram and i know 2 is hot because it comes from the battery and 1 is ground because it has a ground symbol on "it's side"? and then 3 is hot is it?
do the colors correspond to hot and ground at all? i don't get that either...

 

[jht3]

lol. it's like some kind of jailhouse game of charades or pictionary getting straight answers with this low voltage stuff.
like this?

View attachment 2915678

exactly like that. although it doesn't really matter which probes you use in continuity mode

what you are trying to do here is test that the G-R wire is CONTINUOUS. this is accomplished by removing the relay and using your meter to connect pin 1 back to ground. with the horn pressed, you are connecting both ends of the G-R wire to ground and your meter should show a near zero resistance.

voltage flows from the battery POS through the fuse to the relay pin 2, through the coil to pin 1, then to the horn switch. when you close the switch, the coil is "excited" and pull the switch in the relay closed (this is the click you hear). now voltage is able to flow out pin 3 to the horns themselves which are already grounded.

 

[jonheld]

so just to ask again:

for the #3 test you want MM set to Ohms and one probe in slot 1 in the fuse box and the other probe clipped to ground at the battery? or you want the other probe clipped to the POS pole?

(sigh) I gave you step by step directions in post #43 which you apparently did not read. Here is a copy/paste. Please read it this time.

^^^^^^^^^^^^^^^^^^^^^^^^^^
REMOVE THE RELAY FROM THE CIRCUIT.
Set your meter to continuity (OHMS).
Stick a meter probe into relay socket pin 1.
Stick the other probe to the negative battery terminal.
Push the horn switch on the steering wheel.

You should see very low resistance, close to 0 ohms.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The horn circuit is the most basic of all circuits in the truck.
If you plan to continue working on this vehicle in any electrical capacity, I suggest a visit to your local library and pick up a book on basic DC electronics. It will get you familiar with the terminology and common symbols used. There are also very good tutorials online.
Learn and practice how to use your meter correctly and what each setting is for.

 

[landcruiser3DP]

exactly like that. although it doesn't really matter which probes you use in continuity mode

what you are trying to do here is test that the G-R wire is CONTINUOUS. this is accomplished by removing the relay and using your meter to connect pin 1 back to ground. with the horn pressed, you are connecting both ends of the G-R wire to ground and your meter should show a near zero resistance.

voltage flows from the battery POS through the fuse to the relay pin 2, through the coil to pin 1, then to the horn switch. when you close the switch, the coil is "excited" and pull the switch in the relay closed (this is the click you hear). now voltage is able to flow out pin 3 to the horns themselves which are already grounded.

hey man. thanks very much for this.
i used to have this honors math teacher in high school. every time i screwed up the temerity to ask a question about something i didn't understand she would screech "And if you don't know this, you shouldn't be in this class!" sometimes i think of her when i am on here.

it would be nice to be able to document this for others at some point. i mean i am damn near positive i am not the only one that isn't going to learn this stuff in the library.

one thing please? i don't think i understood i was reading the continuity of the G-R wire. meaning i somehow had the impression that the MM was acting as a bridge somehow across the removed relay. but i guess this is of course not the case and what i am really doing is - well one end of G-R (green-red) is grounded at the DS kick panel? so i am just running it back to ground at the battery and testing - well basically i am testing continuity between battery NEG pole and the ground at the DS kick panel i guess?

so in shorthand this is "checking grounds with the continuity setting"?

if so, what is the other test then? jon said "do you get constant +12 at pin 2 of the relay socket"

pin 2 is the connection at the relay to the battery positive terminal? so what is the setup here with the MM for testing? i am testing for 12V through the wire G-O (green-orange)?

how is the MM setup here please? one probe in the pin 2 and the other clipped to battery POS?

 

[jht3]

you aren't testing the relay here at all, just the wiring

to test for voltage at pin 2 you would switch your meter to DCV, put the red probe in pin 2 and the black probe on a ground (battery terminal is great if your leads are long enough). 12V should exist at pin 2 but you need to give your meter a path to ground to measure the voltage. i don't recall if the horn circuit is ignition switched or hot at all times; you'll have to figure that out.

 

[gummycarbs]

On the subject of cleaning terminals, blast out the grime with something like the aforementioned CRC cleaner. Then spray it with Deoxit to remove corrosion:

I've had neglected, 30 year old motorcycle terminals that were clean and glossy after simply spraying with Deoxit, then plugging and unplugging them a few times.

If that doesn't sufficiently clean them, use a soft brass bristle brush:

To prevent corrosion in the future, pack all connectors with silicone dielectric grease. I buy cans of this stuff when it's on sale:

 

[landcruiser3DP]

to test for voltage at pin 1 you would switch your meter to DCV, put the red probe in pin 1 and the black probe on a ground (battery terminal is great if your leads are long enough). 12V should exist at pin 1 but you need to give your meter a path to ground to measure the voltage. i don't recall if the horn circuit is ignition switched or hot at all times; you'll have to figure that out.

hey man,
thanks again for this. i got the second test (test 1 was jumpering pin 2 to 3) but i didn't understand the last one.
jon said "did you get a constant +12 at pin 2 of the relay?"
i am trying to draw it up. MM is set to DC V. and then what please? jon mentions pin 2 on this one i think and you are mentioning pin 1?
also conceptually what am i testing here with this test again please?
also - is the relay pulled in this test?

 

[jht3]

my bad, pin 2. updated my prior reply. everything else remains the same. trust the EWD not my distracted typing!

 

[landcruiser3DP]

my bad, pin 2. updated my prior reply. everything else remains the same. trust the EWD not my distracted typing!

all good. but conceptually please (like in words if i had to explain it) what am i testing here?
test 1: jumpering of pin 2 to 3 - you are testing if everything is intact and works from the relay to the horn ground by bypassing the relay?
test 2: you are using the continuity setting (ohms) in the MM to verify the wiring from the relay to the combo switch in the steering column and the ground for the switch is intact and not losing electricity due to bad or loose wiring or bad contacts in the switch?
> what is this test doing exactly please?

 

[jht3]

your test 1 is taking the factory horn switch and associated wiring after the relay out of the equation. your jumper wire becomes your switch. if the horns go off, you know you have +12 flowing through the relay socket to the horns and associated grounds

your test 2 tests for intact, unbroken wiring and a functional horn switch.

you don't really need to individually test for voltage at pin 2 if you have already successfully passed your test 1.

i'm just repeating what jon already laid out

 

[landcruiser3DP]

your test 1 is taking the factory horn switch and associated wiring after the relay out of the equation. your jumper wire becomes your switch. if the horns go off, you know you have +12 flowing through the relay socket to the horns and associated grounds

your test 2 tests for intact, unbroken wiring and a functional horn switch.

you don't really need to individually test for voltage at pin 2 if you have already successfully passed your test 1.

i'm just repeating what jon already laid out

THANK YOU. so test #3 is testing for unbroken continuous wiring to the POS pole, a working battery, and a working 15A fuse is that right?

 

[landcruiser3DP]

OK. so hopefully some of this is helpful to someone. i've been learning low voltage on my motorcycle over the years but never really put anything to the test in terms of voltage drop (which i still need to learn to test) or any of this kind of more deliberate testing. anyway i wrote it up and will post it in case anyone is interested.
the long story short here is i originally went in to replace a $10 brass or bronze plunger with a spring on it which the internet seems to say is the cause of 80 series horns not working. but i have a 97 so when i took it apart i was confronted with the 96/97 clock spring.
i had replaced the fuse and i had tested the relay in the vehicle by hearing it click audibly. and also since the hazards were working and because they use the same relay as the horn it seemed to me and the guys at NAPA that it would not be the relay. also i cleaned the horn ground which seemed OK so i kind of moved past the relay and a $10 plunger seemed like the next cost sensible move.
then when i confronted the clock spring i just kind of moved into replacing the clock spring which definitely was an adventure in itself. documented here in all its glory.
anyway if you have this problem i finally replaced the relay by ordering a NAPA relay. i'll post a part number but it is $20 compared to over $80 for the toyota one.
a couple other notes are rhat my relay seems to have failed in a weird way that may be related to the coil in it. basically from what i can tell if you remove the relay for a period of time or disconnect the battery the horn will work for some period of time only to start to "not kind of work". what is additionally confusing is the 96/97 steering wheel (at least) has four sets of contacts. so when it is "not kind of working" it is not working in a way that appears to depend on which way you push the airbag - making it seem in a way like the problem is in the wheel.
i took apart the relay after getting a new one in to have a look and it looks about as clean as you could hope to see.