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Discussion Starter #1
'05 K24A3 JDM Engine & EMS going in Bertone/Fiat X1/9..

I'd like to use the built in (the the ECU) AC compressor control. Looking at the wiring diagrams, I can't figure out where the signal comes from that switches E18 to ground & allows the relay to engage the AC clutch. Looks like E11 & E24 (CANbus signals high & low?) are used to govern it? If so, I don't see how to bypass that for the old school press an ON switch setup my car has. I can wire a relay to use E18 as the ground leg, but without knowing how to apply a signal to the ECU to tell it it is OK to ground E18, it's not gonna work out....

Any pointers? Anyone made this work in a non-standard setup?
 

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Looking at the schematic the climate control module is sending a ground signal to the multiplex control unit when it is requesting the clutch on. The multiplex is then sending the request to the ECU over a communication line. Unless you have the multiplex unit you cannot use E18 for the AC compressor.
 

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Discussion Starter #3
Thank you for confirming my suspicions. I just wired in a relay using a regular path to ground instead of using E18.
 

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Discussion Starter #4
An additional problem as a result of not using the AC signal - the idle compensation for the AC loading doesn't work - the idle rpm's drop significantly, almost stalling. Trying to figure out another way to indicate to the system that idle compensation is required...
 

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The idle is supposed to jump up when a power steering switch is flipped. Like if turning the wheels sharply while not moving the idle should jump up.

The power steering pressure switch (PSP) is a normally closed switch which grounds pin E16, when the load is high the switch opens. The ECM no longer sees ground on this pin so the idle is bumped up. If you currently don't have this pin going to anything you would need to wiring something in and then maybe relearn idle before it would work.
 

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Discussion Starter #6
The idle is supposed to jump up when a power steering switch is flipped. Like if turning the wheels sharply while not moving the idle should jump up.

The power steering pressure switch (PSP) is a normally closed switch which grounds pin E16, when the load is high the switch opens. The ECM no longer sees ground on this pin so the idle is bumped up. If you currently don't have this pin going to anything you would need to wiring something in and then maybe relearn idle before it would work.
Many thanks - I was just reviewing the Idle Control section of the RSX manual & saw the reference to the PSP circuit - that would do the trick if I can an appropriate switch - or maybe the coil circuit of a relay would be sufficient path to ground?

Also, do you know the function of the SCS signal/circuit? I see reference to "jump the SCS with the HDS" - not sure what function serves. When I wired the ECU, I thought that was a service indicator, so I wired it to a LED in the cluster, like the MIL. I'm now assuming that is not it's function :)
 

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SCS stands for Service Check Signal. If you short this pin to ground and then turn the ignition switch on the MIL/ABS/SRS lights will flash indicating what faults are active.
 

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Discussion Starter #8
SCS stands for Service Check Signal. If you short this pin to ground and then turn the ignition switch on the MIL/ABS/SRS lights will flash indicating what faults are active.
Thank you - I will rewire it to the OBII port where it's shown in the manual.
 

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Discussion Starter #9 (Edited)
The idle is supposed to jump up when a power steering switch is flipped. Like if turning the wheels sharply while not moving the idle should jump up.

The power steering pressure switch (PSP) is a normally closed switch which grounds pin E16, when the load is high the switch opens. The ECM no longer sees ground on this pin so the idle is bumped up. If you currently don't have this pin going to anything you would need to wiring something in and then maybe relearn idle before it would work.
OK - the other problem is that I went through the IACV test procedure again, and it fails at step 15 - no vBat

 

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Discussion Starter #10
Problem is, I've gone through 2 new IACV so far, don't know where to buy one that is a reliable source & not just an over-priced cheapo one.
 

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Granted you have a stock '05 Accord throttle body the part number is 16022-RAA-A01. You can order from a site like HondaPartsNow or something.
 

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Discussion Starter #12 (Edited)
Granted you have a stock '05 Accord throttle body the part number is 16022-RAA-A01. You can order from a site like HondaPartsNow or something.
I'm using the K-Tuned TB - I can use any of the 2-bolt mount IACV, the heater circuit isn't used. From Honda, those are several hundred dollars - I'll have to research a reputable aftermarket brand besides all the cheapo versions.

EDIT: Found an Honda-packaged (PRB version) valve for 200, that's the cheapest I've seen any going for. I went ahead & ordered it.

 

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Discussion Starter #13 (Edited)
The idle is supposed to jump up when a power steering switch is flipped. Like if turning the wheels sharply while not moving the idle should jump up.

The power steering pressure switch (PSP) is a normally closed switch which grounds pin E16, when the load is high the switch opens. The ECM no longer sees ground on this pin so the idle is bumped up. If you currently don't have this pin going to anything you would need to wiring something in and then maybe relearn idle before it would work.
Found another issue - the IACV connector I used has the wire terminals marked backwards - 3 2 1 instead of 1 2 3

This pic I found online, but it matches the diagnostic guides








I thought that I had found the cause of all my woes - but when I reversed the wires to match the factory settings, the engine can't be revved - it goes completely flat & looking at the logging screen I can see there is no throttle signal at all. I reversed the IACV wires back the way I had them, and it runs OK again, besides the idle problem that I have had all along.

Not sure how to proceed, as if I connect the new IACV the same way when it arrives, I'm assuming I may damage the circuitry. I don't understand how that screws the TPS settings either .
 

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I don't know what you mean by the engine can't be revved at all. You're using a cable driven throttle, right?

You also have a stock '05 Accord harness? My schematic shows the wires should be black, blue/red, and yellow/black.
 

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Discussion Starter #15
I don't know what you mean by the engine can't be revved at all. You're using a cable driven throttle, right?

You also have a stock '05 Accord harness? My schematic shows the wires should be black, blue/red, and yellow/black.
I'm using an '05 JDM TSX harness, with the DBW TB (App Sensor) rewired for TPS & IACV, with the appropriate wires moved in the "A" connector for TPS power, signal and signal ground (A20 A29, A23), and IACV signal (A12)

What I meant was the system is not recognizing the throttle change and goes full lean off idle. I can see in the logging window that the TP % is not changing. Example: (testing throttle angle here, not running)




It's just wierd. I also realized that based on the factory wiring diagrams, my TPS was also reversed 3 2 1 (L-R), but when I rewired it 1 2 3, the throttle angle reads in reverse in K-Tuner, so I put it back as it was. I see that in the diagnostic testing the K20Z1 uses the opposite wires (step 9, pg 11-125 RSX manual), so the TPS can clearly be wired either way, depending on application. What I don't understand is how or why having the IACV wired correctly would cause the throttle angle to not be recognized.
 

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Discussion Starter #16
On the plus side of all this - going back to the original reason for the post - I found that I can designate other triggers for the AC that will negate the need for a CANbus input

 

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Discussion Starter #17
Found the cause of the problems - the aftermarket IACV was backfeeding the system. I installed a new OEM (Honda-packaged) Denso unit today, and rechecked all the diagnostic values - this time I had the correct values for all tests including vBat between A12 & ground with A connector unplugged.



 

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Discussion Starter #19
Glad to hear! I've never heard of anyone having success with non-OEM IACVs.
Seems to be true. I bought two of the Amazon vendor versions - different manufacturers based on construction when I dismantled them to look inside - neither one worked for shit. You would think there would be some middle ground between the $30 crap & the $200+ OEM, but doesn't seem like it.

I'm having similar issue with the left inner CV - I bought a FEBEST 44310-TA0-A60 - and that outer seal is seeping. The shaft has a fair amount of radial deflection (slop), more than I would consider normal, for a Volvo anyway. Honda's I don't know enough about. I also have the MFactory LSD, so it could be the diff, for all I know. I don't have the orginal inner CV to compare 'feel'. Bottom line is same scenario - either about $50 for an aftermarket or close to $300 for OEM... :(
 
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