1st Gen Haltech ECU Discussion

AC systems dislike you running them at high RPM, causes pressure spikes and they cycle too frequently wearing out the clutch and reducing cold air output. Stock computer logic turns it off under high engine load and turns it off if the engine is headed for an overheat (ie pulling a tough grade in summer). Also made it so it would turn off if idle was super low for some reason to avoid a stall condition. I just mirrored the logic to my best ability so I didnt have to consciously turn my AC off in the summer.

 

I haven't no, actually to be honest I've only ever broke 220° once in any Toyota and it was in fall pulling a 14% grade for 10mi in Wyoming. But it took me all of 3 seconds to add that statement into my rule so why wouldn't I?

 

Just curious, at what engine load percentage does it cycle off?

 

Stock ECU that is...

 

Interesting. AC run conditions aren't something I considered to add to the ECU file. On the SNP adapter I have, the ECU can't see a state change of the AC from whatever wire it's connected to. Because the voltage change is so small, from my understanding. I was told to run a direct wire from further down the harness off the connector going to the compressor in order to get a solid switching signal.

The air con output enable is turned off in my tune and still works fine. I thought the AC operates separate from the ECU other than offset RPM's

 

You know I don't know for sure, I could have done this rule with calculated load but I chose RPM since it's just easier.

Oh, I don't know. I think it has a few conditions in which it turns off for "load". If I stabbed the throttle from a stop stock it would operate until around 2500rpm and then drop off if I didn't let off the throttle a little. At a certain lesser load it would stay on until I cross the 3500rpm threshold roughly. It is using RPM and calculated load but what that calculated load is I do not know, it seems to depend upon speed. I couldn't find any real info in the toyota EFI tech manual about hard and fast values.

SNP has the AC sense configured in reverse, I corrected it on @Digiratus' truck when we first installed his SNP kit. It senses AC on just fine now. The SNP kit uses a Boomslang harness and what I've noticed looking at their wiring charts for other trucks is that they treat the AC1 (AC sense) signal and ACT (AC cutoff) as inputs but only AC1 is an input the other is an output. Both use ground side switching and SNP had the thresholds configured for high side switching. You shouldn't need to wire it into the mag clutch to get a solid signal, you just have to know what type of circuit you're working with at the control level and evidently they didn't. Another bonus of using the control side is the AC amplifier warns of turning the clutch on before it does so you aren't just reacting to a load at the same time it happens, it gives a split second to start correcting RPM beforehand. But yes the AC amplifier will do its thing entirely without ECU intervention, those two wires just let the ECU intervene and understand when there will be additional load.

 

I only have DPI2 set for A/C Request switch input, no output configured for AC. Or do you mean ACT as an output that doesn't run through the ECU?
When you say high side switching, do you mean rising edge vs falling edge? Mine is configured to falling edge, but still have no voltage change upon switch state change.

 

In NSP can you generate a wiring allocation chart so I can see what I/O you have avail?

 

Keep in mind for a 3RZ

 

Okay now I can answer your questions. So putting the AC Request to a DPI may be possible but it really is for sensing frequency inputs not constant state stuff and as such has no voltage sense/cutoff settings. So here is where the explanation becomes a bit muddy and I'm sorry it has to. Boomslang makes the patch harness for SNP, and when Boomslang makes a harness they make a nice little chart that marks the name of the wire in Toyota terms and where it is patched to in Haltech terms... SNP doesn't pass this piece of paper along to their customers and it leaves a black hole in knowledge for the next guy (or the customer who has features that still don't work) to figure out.

It gets muddier still in that Boomslang, while super responsive and capable in customer service and wiring skill doesn't always know what every OEM wire does (I want to be clear I am not shaming them or calling them out at all, I love their customer support and they support so many vehicle makes and models it would be unreasonable to ask them to get everything right anyway) and doesn't always patch them to the proper Haltech I/O option... and in the case of the 750, doesn't pass along every bit of OEM I/O because there just aren't enough pins available. So in the case of my patch harness they only passed along the ACT pin but they wired it to an input... this problematic because it is not an input and it doesn't let the ECU know a damn thing as to the AC state. But that's the only AC pin they patched from the OEM harness so I had to wire up AC1 myself (which is the sense wire) as well.

So here's where we are with yours, I don't know if the wire that's currently in DPI2 on your ECU is ACT or AC1... if it is AC1 I would suggest moving its pin from A13 to A15 and then I can show you how to set voltage thresholds on an AVI and get you going with AC sense. However if that pin they patched is ACT then it needs to go from A13 to A5 and we can configure the generic output as I showed above to get AC cutoff working for you and I can walk you through how to grab the AC1 signal and make a new pin to also have it so we can wire and configure AC sense as well. I'm sorry it has to be that convoluted but that's the downside of not having the paperwork from Boomslang.

 

I just would have assumed the temperature would be the presiding condition, not high RPM...

 

They're all "or" statements so order has no importance, order them as you please.

 

not what im saying... but it doesn't matter

 

I'm more concerned about burning the AC compressor up from constant high pressure bypassing, there's a reason manufacturers turn them off in some conditions. The temp statement is more for saving the engine, and as you say, shouldn't be a concern if I'm watching my gauges. The AC system watches its evap temp like normal still either way.

 

FYI for this thread, I have the following reports upcoming once I receive some parts:

- PRD2L single wire input & splicing & conditional config to provide Park vs Drive for certain tables (will be made available for purchase)
- PNP Speed sensor splicing & config in HT (for bigger tires)

Further down the line:

- DIY gauge (pod?) kit for HT CAN reading (will be made available for purchase)
- Transcoder bridge for onboard J1850 OBDII from factory ECU and HT OBDII and/or CAN to standard OBDII plug, so appropriate readings can be read and combined appropriately from both, for those who run these spliced. Will likely be built into the gauge code.

 

Just a heads up later models aren't J1850 on the stock OBD, its a later standard

 

Ok so they did switch to the CAN pins? Was wondering

https://www.scantool.net/blog/which-obd-ii-protocol-is-supported-by-my-vehicle/

 

Gotcha. Makes total sense. Just need to verify what wire is going to that input; ACT or AC1. Thanks for the help.
Didn't know that boomslang made the SNP adapters. From my understanding I thought SNP did the resin mold in house that encapsulates the receptables for the OEM ECU plugs. I honestly wish it wasn't cast in resin because it prevents me from making any wiring changes at the adapter

 

same

 

ditto