Hey there I'm new here I tried to put my car type in my signature but I can't seem to figure it out. Anyway I recently picked up a 98 accord ex 2.3 vtec 5 speed with a surging idle previous owner said he changed iac and tps it does the surge even on deceleration as well it bounces between 1 and 2k rpms. I've bled the coolant I'm going to check out the pcv valve this evening but I was wondering if any one has the wire colors for the iac and what there outputs are supposed to be I've searched and found out one is black and yellow and goes to ECU. I'm trying to find out all the colors and and we're they go to and what I'm supposed to see for voltage. I'm trying to ohm them out from the sensor back to the ECU if anyone can shed some light on this I would appreciate it it's 3 wire iac thanks so much in advance

P.s I forgot to mention when I unplug the map sensor while running the idle quits surging as bad if I unplug the iac it idles just fine

 

Stop by a parts store and have them scan for codes. Post any codes you get on here.

It was possible to switch connectors between the map and tps sensors on the 94-97 accords. Not sure if this could happen on the 2000 accord, but an easy check.

The wire colors to the TPS should be grn/blk, red/blk, and yel/blu.
The wire colors to the map should be yel/red, grn/wht, and red/grn.


For the IAC wires: Blk/blu is the control from the PCM. Blk should have continuity to ground. The yel/blk should have 12V.

I also suggest purchasing the shop manual for your car. You can get a pdf for your accord for $22 at automanualsource.com. It is invaluable when trying to troubleshoot problems.

 

Thanks for the fast response! I have a scanner and the only code I get is p0519 and I appreciate the wire color codes but my iac has 3 wires if BLK/blue has continuity to ground is that with key on or off? And is 12v supposed to be constant or just while running? What about the third wire ? Or maybe I'm reading it wrong how many volts is the signal supposed to be ? Is it 5 volts ? Thanks for the help

 

Is your code P1519 or P0519? I don't have a P0519 listed in the shop manual.

Key should be on and not running for the yel/blk wire to have 12V.

The blu/blk wire gets a signal from the PCM to adjust the valve. EDIT: This a pulsed ground signal. You may be able to use a proper sized test light, where the test light is hooked up to power. The light should flash if it is getting signal.

 

It's p0519 it translates to idle air control system performance

 

P0519 isn't listed in the 98-02 accord shop manual. Just want to make sure your scanner is reading the right code(s). You may want to take your car to a parts store and have them scan for codes.

The input tests for the 3 wires is still a good place to start for testing the wiring.

 

Ok so I did what you said I get 12v with key on I get good ground now when I checked the signal I used my test light and my voltmeter my test light isn't the greatest and with the negative clip on the ECU signal and the probe on positive it didn't light up but my meter was jumping signal around and when it was on the battery the car ran fine but as soon as I lifted the test light probe off the battery the idle started jumping again ? Any ideas on this ?

 

I have positive and negative I hooked my test light up with the clamp on signal probe on positive and my meter as well the voltage jumps all around consistent with the idle but the weird thing is when my test light was going from the battery to the signal positive on battery negative clamp on signal wire the car ran fine but as soon as I removed the test light from the positive on the battery the idle went haywire again any thoughts on this ?

 

I'm confused on how you have your meter and your test light connected. Are both your volt meter and your test light connected to the + battery post? Are the other ends connected to the blk/blu signal wire?

Also, are you testing by backprobing the connector to the IAC, so it remains plugged in? Or is the IAC unplugged when you are doing your testing?

 

Iac is unplugged just probing connector you had said it was negative pulse so I have the negative of test light and negative of meter on signal wire and positives to the battery I'm just confused why it would run fine with the test light hooked up to the signal wire and the positive of the battery the iac isn't plugged in at all thanks for you time this far