Hi HT, having a hard time with this one.

W/ key on I have the TPS calibrated to .45
Running or not Im getting the voltage from .45 jumping to .7 when i put down the brake, and up to almost .9 when i turn on the headlights. So whenever I turn on things in the car the voltage goes up at the TPS signal wire. tested the ground and 5v refrence, they check out just fine.
This is trowing a code for voltage input to high.

Any ideas?

oh yea, h23v in a ej all obd2

 

i think you might have your plugs around the wrong way. The TPS plug also fits on to another sensor in the near area (eludes me at the moment its 8am sunday morning and been called into work)

Also your TPS should be set to 0.5.

 

its the right plug. I have the right voltages at the sensor and at the ecu. if it was not pluged in right... I would not have the nice sweep that i do.
well, almost the right voltages. set to .45 closed but when i start it, volts go down to about .324, then when I brake... up to .7ish... and headlights... .9ish.


ELD?

ummm.... gah!!!

 

Sounds funny.

The correct setting for the tps is actually, .45-.5 doesnt matter it can be .46,.47.48 etc.

As for your problem, it sounds like your getting some weird extra power added when the alternator is running.

What I would do?

Test the voltage for that wire at the ecu. If it checks out good at the ecu, just replace the wire.

 

its not good at the ecu.

I had the fluke down at the ecu when i noticed that the voltage of the tps would go up the more i turn things on, radio, headlights, brake pedal, etc.

I dont get this, the ELD should not cause this right? I dont want tto swap the harness becaus I dont thing the harness is to blame. Nor the ecu as Ive tried a few.

SO stump'd.

could the ALT be acting up? is that even possible?

 

Oh, I did replace the wires... sensor...

The volts seem to being coming out of the ecu, I dunno though, id have to cut the wire and messure again. tired of cutting wires tho. this is killin me, never in a million years have I been this dumb-founded with my own car.

Oh, I use to get a headlight surge before my swap. so im still thinking that the eld could be an issue, but i dont see how.

 

Go have your alternator tested it doesnt take that much to do that

 

You also might have high resistance on the ground side of the TPS. Check for voltage at the green/white wire with the TPS connected, KEY ON, ENGINE OFF. Should be 0v. And check all the grounds while your there.

 

Yea, I did cover that. I said..

" tested the ground and 5v refrence, they check out just fine."

the ground is a ground and the 5v ref is a 5v ref.

eld or alt is all i can think of, so I guess im gnna try replacing the ALT. this is gay, this should'nt be so weird. Im so lost.

 

Either you have a bad TPS or you have a short in the wiring. You need to get a set of tips for your multimeter with the needle ends. They will poke right through the wire and you wont need to cut. Check voltage at the ECU and then backprobe the TPS. If you have a clean signal at the ECU but not at the sensor itself then there is a short in the wire. A loose ground can also cause this, check for continuity on all related grounds.

 

DO NOT POKE THROUGH THE WIRE. This is basic electronic stuff. Poking though a wire will open it up to moisture, cause corrosion and very high resistance. Wires also have an amazing ability to wick water, so not only the point you poked into the wire will become corroded, but the whole damn wire. The proper way is to use a t-pin and back probe at a connector. And it all depends on what you're measuring anyway. Also my bro suggested using a break out box.

Too me, I kinda doubt it's the alt. I'm thinking a short to power somewhere in your wires. Then again the short could be in the stator windings in the alt... Also check any capacitors or diodes on that circuit, they could be letting a voltage spike through. Also make sure your battery is good, it kinda acts like a capacitor and provides even electricity flow, and if damaged or low charged can cause power fluctuations. Also check for EMI in the vicinity of your computer and sensor. If your radio makes funny noises when it's on like clicking or whining noises that shouldn't be there, you could have an EMI issue.

Also, if you don't already have one, get a wiring diagram for your car. They help.

 

I did this, as i said above.
I said I was going to cut the wire to see where the extra volts are coming from, ecu out or tps in.
I replaced the TPS twice, I ran new wires direct also, still same issue.
again, all related grounds check fine.
I noticed a headlight surge some time ago, might be related. I dunno.

Bat is good. the stator is a poss, ill check that out, thanks.
I tried dif ecus so a Capacitor might be out of the question.
No raido noise.
yea, i have a wiring diagram. Im confused because i changed all the componets to the tps, sensor, wires, etc.

 

well you got me pretty much stumped. hell though, we went over this in class today but the only malfunction we really went over is the tps contacts wearing out/burning up etc in the potentiometer. I'll ask my instructor tomorrow. I'm rather curious myself.

All I can think of is it's a short, or your ECM is screwing up.

 

yea, its weird. its such a simple sensor too.
as you said a Potentiometer, which has a perfect sweep, and perfect refrence volts and ground.

Im gonna test at the VSS and see if Im getting more volts to its signal by turing things on. maybe its the whole car and the tps is the only sensor thats that particular and giving a code

 

WTF kind of help is this.

I have been using the probes for many years now, and have had no issues.

And so has the rest of the world.

The only reason I say it is alternator related is because, if the tps checks out okay, with just battery power, than it checks out bad when the car is on, its obviously coming from something to do with the alternator, because the battery and altenator are the only 2 different power sources for the engine.

The battery runs the power while the car is not on. Once the car is on the power comes from battery.

Doesn't mean that it is the reason.

 

is the eld in the alternator on the obd2 civic? it is right?
I think the alt or eld has to have something to do with it. its the only thing that would make any sence to me.

"The ELD sends a signal to the
ECM/PCM that’s proportional to the electrical
demand. The ECM/PCM switches the alternator
between high output and low output depending on
several factors, which include electrical demand,
battery charge level, and the driving cycle"

Instead of back probing, I was going to cut the wires and see if the extra volts are coming from the ecu out or the tps input. I dunno, is that something worth testing. god I feel stupid for this

 

Just tested my ALT and its showing 14.67

...


FAIL!!!

I hope thats my issue. replacing soon.

 

How is that fail. Technically, thats correct.

Your ELD should be built into your under hood fuse box. Atleast it is in the Prelude.

Also dont go hacking up your harness on a hunch.

 

to know what side the extra volts are coming from... I have to cut it.

Umm yea 14.67 is fail. voltage regulator in the alt is toast. correct volts would be 13.5ish anything over 14.5 is overcharging. and when I put more of a load on the electrical systme... it goes even higher. which would explain why the whole cars signal volts are too high. the cap is only going to reg for a 13.5 amount.

no? rule of thumb is 14.5, at least thats what my books tell me. and techs.

im a good listener and all ears to opinions!

 

Hmm, seems fine to me. I have had alts put out 14 before with no issues.

But if thats what the book says, than its true.

 

Unless my alternator was failing, I've never had a honda alt put out less than 14.5. A truly bad regulator is hard to judge when it comes to over-charging. Especially when you have aftermarket electronics installed.

You will probably get the same reading with the new alternator, so you should dig a little further before you spend your cash.

 

I have had alternators spike in the past to 20 volts, and blow a handful of fuses.

My alt runs around 13.5 with all electronics on, and smaller pullies.

 

Yesterday I discussed this with my brother and he mentioned it's probably the alt voltage regulator or diode, which will cause voltage spikes. Prolly caused your headlamp spike too.

On an unrelated note- just because you and everyone else pokes holes through wires, it doesn't mean you should. Just like you shouldn't place a lit cigarette on top of a battery. I've seen people do it, and be fine. But better hope your luck doesn't run out. I've seen antifreeze leaked on a passenger floorboard of a car because a coolant temperature sensor (i forget exact cause) allowed antifreeze to come into contact with the wires and it wicked antifreeze right to the ECU, which in turn dripped onto the floorboard. Computer was fried.
Number one cause of green wires is poking holes through the insulation.

 

had a GM tech in here the other day and he says its a ground issue period. i checked the ground and it seems solid.

yea 13.5 is what an alt should be, from all that i have seen and tested.

So Im gonna look into grounds for a bit longer.

Thank you for all your help. Ill post when i have issue solved.
thanks again

 

having a similiar problem please let us kno if a new alt. fixed it...gl man