TX_RX

So I have started to get my car ready for Texas state inspection. So far, the list is:

1)Horn doesn't honk
2)Wipers are worn out
3)Tires are worn out (maybe, they might fly)
4)License plate lights don't light up

Just tonight I replaced the windshield wipers, and replaced the license plate bulbs. The bulbs still would not light though. A multimeter shows continuity between the red/blue and black wires, and resistance reads about 100ohms (with the bulbs disconnected).

As for the horn, the horn itself does work. I shorted between the green/white and green/red wires on the big CPU connector to bypass the relay, and the horn honked. However, that was the point I decided to give it a break. Next I will short Green/Orange to black on the same connector to see if the relay will work at all. Finally, I will try to see if the switch works. There are only 3 major parts to the horn system (horn, relay, switch), and I have eliminated one possibility already.

Right now this will just be a running log of my work to make the car inspectable. If anyone has advice, feel free to chip in. My hope is this log might help someone in the future with similar problems.

TX_RX

And I feel stupid now. The license plate lights only come on with the headlamps. I am no longer working on a motorcycle, it's a car, DRL is not required in the US.

Plus that makes sense to see 100Ohms across the Red/Blue to ground, there are a bunch of other bulbs in parallel.

So 2) and 4) down. I should have this ready in no time!

RXSpeed16

iTrader: (41)

No horn (#1) is due to bad solders in the cpu. It's located on the left side of the driver footwell behind the panel. Remove, disassemble and re-solder where the pins connect to the board and anywhere else there are cracked solders.

Stevobob

iTrader: (1)

Hit up craigslist for some used-but-good tires, loads of people want to unload two-season-old tires with plenty of tread that would be perfect for passing inspection.

TX_RX

Thanks for the comments. I did read about the solder joint in the CPU. The CPU is actually right here next to me on my desk. However, I prefer to troubleshoot first. My grandfather told me to first understand the system, then figure what is wrong, then fix it.

To that end, I tested the switch by putting my multimeter set to "continuity" between the green/orange wire and the black wire and pressing the horn. I did see something, but it wasn't solid continuity. I switched it to ohmeter mode and I couldn't get a stable resistance reading. So I removed the steering column housing and found out how the horn works.

There is a horn/turn signal cancel/angle sensor attached to the steering column. The sensor has a set screw attached to it. The horn wire, which is green/orange, is soldered to the set screw's threads. The set screw slides on a contact ring attached to the steering wheel. The steering column is grounded, and inside the steering wheel there is a large ground plate that is grounded to the steering column through the center nut attaching the steering wheel to the column. The contact ring is attached to the two horn buttons by wires, and when you depress a horn switch it grounds the contact ring.

So in my case, I checked the continuity from the green/orange wire on the relay box connector to the green/orange wire soldered to the threads. That was perfect, so the wire from the relay box to the sensor was good. However, measuring from the sensor wire to the contact ring was bad, and measuring from the connector inside the steering wheel to the contact ring was bad. I also observed that the contact ring was filthy. So I think this is a big part of my problem. I got some contact cleaner from fry's today and some wire brushes.

Now, I also tried at the relay box with the connector connected to short from green/orange to black. This should have triggered the horn relay, but it did not. So I think that there is also something wrong in the relay box too. I have a 13.8V 4A DC power supply, so tomorrow I am going to set up a test to see if the relay will trigger. I measured the resistance across the relay coil and it was about 80 ohms. At 13.8V that's 172.5mA, so I hopefully won't pop my power supply fuse.

TX_RX

It didn't go well. I got the horn running, but apparently the taped on tail lamp lens won't pass. Plus, and I feel unbelievably stupid for not noticing this, but apparently one of the lugs on the back right wheel is broken. Plus the tires are definitely not acceptable. So I am getting the ball rolling on those items.