Builds Another Texas LS1 Swap

[warpdriv]

Hey Wayne, how's it going? Thank you for the complement! I do not have a wire from the computer. But it does sense a load and idle up. I just wired the black wired from that connector along with my fan high relay so when I engage the AC the fan runs on high. Very simple.

 

[rockrod]

Jeff,

Does your ac ON input go to the GM computer so it idles up and such? How does it work for you? I got my A/C kickin, but man I'm wondering about the a/c input. I'm testing that today. I also have three wires to hook up today and I'll go test the cruise control.

I cut the three wires on the steering column for the factory cruise switch. See, Toyota uses a "ground" type system, and GM uses an "12v" on system. Meaning when the system sees 12v it activates, and for toyota when it sees ground, it activates through the cruise control ecu. I hooked up the upper brake switch and man alive how it changes things with converter lock up etc. I've also changed my shift points and lock up times etc. I firmed up the shifts etc, and I REALLLLLY like it.

Yours is looking real good!

*EDIT*
This is taken directly from the HVAC description section of the manuals. I have access to ALLDATA Pro, so I have every wiring diagram available.

"The manual HVAC system is a dual temperature zone system. There are 2 separate air temperature levers. Moving the air temperature levers to the upward position diverts most of the airflow through the heater core, which increases the outlet air temperature. Moving the air temperature levers to the most downward position diverts most of the airflow around the heater core, which decreases the outlet air temperature. The air temperature offset can be as much as 16.7°C (30°F) .

Pressing the A/C button enables the HVAC control module to request A/C compressor engagement and turn ON the A/C button LED. The HVAC control module sends a class 2 message to the powertrain control module (PCM) for A/C compressor engagement. The PCM will provide a ground for the A/C compressor relay enabling it to close its internal contacts to send battery voltage to the A/C compressor clutch coil. The A/C compressor diode will prevent a voltage spike, resulting from the collapse of the magnetic field of the coil, from entering the vehicle electrical system when the compressor is disengaged. Defrost and Defog mode selections will request A/C operation but not turn ON the A/C LED.

The following conditions must be met in order for the A/C compressor clutch to turn ON:
The ambient air temperature is above 4°C (40°F) .
The A/C low pressure switch signal circuit is grounded.
The A/C refrigerant pressure sensor parameter is less than 2957 kPa (429 psi) .
The PCM receives an A/C request from the HVAC control module.
The engine coolant temperature (ECT) is less than 121°C (250°F) .
The engine RPM is more than 550 RPM .
The throttle position is less than 100 percent ."

Wayne

Wayne, IIRC you have a DBW setup..

At any rate, I am working on a solution to get the PCM to bump the idle for the DBW motors.

Here's a thread I started.

https://forum.ih8mud.com/80-series-tech/605779-air-conditioning-after-vortec-swap.html

Since the a/c request occurs over the class 2 serial data, you have to have the a/c control head from a donor gm truck to get it to work.

 

[rockrod]

Hey Wayne, how's it going? Thank you for the complement! I do not have a wire from the computer. But it does sense a load and idle up. I just wired the black wired from that connector along with my fan high relay so when I engage the AC the fan runs on high. Very simple.

your motor is drive by cable, isn't it?

 

[wayneosan]

your motor is drive by cable, isn't it?

no his is also DBW. I use EFI Live and HP tuners, and for my truck I used EFI live, so I've been able to play. I've messed with it and it got better. I'm going to solve this today some how.

Do you know what input switches from say, "TOW" mode to "NORMAL" mode?

I was tempted to just get an HVAC control module, but there would have to be the sun load sensors and everything else, including the motors I believe it runs. If they weren't there, I *think it would throw a DTC in the HVAC system.

I'm trying this today. It's all about engine torque. Set the engine timing map at and around idle, including the idle timing, to low values giving low tq. RPM should drop, or idle correction trims should go positive. Then increase idle airflow. RPM should be back at commanded values. Now start datalogger and record what ign cells the timing values move into, and raise the timing 20+ degrees in those areas. That should help. There is a separate idle timing comp, but that can get rather erratic as there is an abrupt transition from idle to off idle. Doing it in the main map will lead to a smoother transition. The deal is, running say, 5 degrees of timing at idle is ok, and when the load slightly increases if you run 25 degrees, that increases tq and will help raise idle. I do it all the time on cars with big cams, so in theory it should work here.

 

[rockrod]

no his is also DBW. I use EFI Live and HP tuners, and for my truck I used EFI live, so I've been able to play. I've messed with it and it got better. I'm going to solve this today some how.

Do you know what input switches from say, "TOW" mode to "NORMAL" mode?

I was tempted to just get an HVAC control module, but there would have to be the sun load sensors and everything else, including the motors I believe it runs. If they weren't there, I *think it would throw a DTC in the HVAC system.

I'm trying this today. It's all about engine torque. Set the engine timing map at and around idle, including the idle timing, to low values giving low tq. RPM should drop, or idle correction trims should go positive. Then increase idle airflow. RPM should be back at commanded values. Now start datalogger and record what ign cells the timing values move into, and raise the timing 20+ degrees in those areas. That should help. There is a separate idle timing comp, but that can get rather erratic as there is an abrupt transition from idle to off idle. Doing it in the main map will lead to a smoother transition. The deal is, running say, 5 degrees of timing at idle is ok, and when the load slightly increases if you run 25 degrees, that increases tq and will help raise idle. I do it all the time on cars with big cams, so in theory it should work here.

let me know how it works for you.
I have been chatitng with a guy over on LS1tech and he used the control head from a 2003+ truck. Basically, he wired it in to the serial network, supplied battery power to the correct leads, then used the trigger wire that would normally activate the a/c clutch to supply 12vs to the switched power lead on the control. Since the control will remember it's last know setting (ie a/c was on when truck was shut off) you can basically use the a/c clutch trigger wire to mimic the truck being turned on and off. I was concerned that this would eventually kill the a/c control head but he reports it's been running like this 2plus years.

At any rate, letting the pcm control the a/c clutch means that it will also idle compensate as well. Of course, you then have to wire in the a/c pressure switch and supply a ground to the pcm low pressure switch input. The a/c pressure switch is tricky because it's a variable pressure input from 0-5v and feeds the pcm real time a/c refrigerant pressures. My thought is to find what's considered to be the normal range pressure and then use a resistor to mimic an input voltage (say 4v) so that the pcm knows there's normal pressure in the lines. You still have a safety for overpressure because the land cruiser a/c amplifier is still in the circuit and can react to it's pressure switch. I think the artificial signal to the pcm would need to be on the low side so that it always commands the compressor so that it thinks it's pressurizing the system.

clear as mud?

I just finished up killing one more DTC. I didn't have my fuel tank pressure switch wired in - now it is and viola, no more DTC.

My tuner is sending me a second PCM - should be here on monday. I requested him to remove the DTCs for the low and high cooling fans because I am not using the PCM for fan control.

he also removed torque management

I think I need a new MAF sensor. I am getting some high rpm pinging (even on 91 octane) and I have a weird dead spot right at 2650 rpm. It just falls on it's face right at that point. very strange.

 

[wayneosan]

resister = plus 1 here. I'd do that too if that was my route. I surprised it works without the sun load sensor. Maybe that's only in the auto climate control heads.

Makes no sense to put the pressure sensor in.

If it really bugs me, I'm going to go ahead and put a momentary switch, such as nitrous switch, on the pedal, and use a relay to open the compressor circuit. Then use the same relay and the starter power wire to act as a starter interrupt on the a/c circuit. That's all it did from Toyota I believe. Wonder if someone could confirm that on their stock truck?


Ok, going on a test drive, and have the cruise wired up. !! If this works I'll let you know Jeff, and you can do it too and your factory cruise on the column.. According to the descriptions, the only other module it communicates with is the ABS.



PS, EMAIL ME A LOG and I can tell you what's going on. I am de tuning mine to run on 87. I had been running E85. was knocking like crazy on 87, I mean, I've already taken out like 8 degrees of timing!!

 

[rockrod]

The red/blue pcms are the ones that you can put a 12v in signal from your a/c compressor circuit and it will activate the idle compensator when a/c is called.

The blue/green pcms get the a/c signal from the serial data wire. serial data is not voltage so you can't feed voltage and expect the pcm to do anything. you have to send the correct code in binary.... 00110001010 - something like that.

Do you know what color the pcm connectors are in your harness? Mine are the blue/green which is from the 2003 a later LS1 and vortec motors.

2002 and earlier use the red/blue and don't have the serial data wire. They use something called UART or something like that.

The color of the connectors is going to determine how you get the pcm to compensate idle when a/c is called.

 

[wayneosan]

Yes, I have the later DBW ecu.

Ok, so Jeff, here's the summary.

My idle is rock solid with and without A/C. Cruise does need the serial data from the ABS module. The cruise needs to know if abs module is active or not. See, I believe traction control activates the abs and if abs is active it shuts off cruise. ERgo, no cruise unless abs module is happy.

It took some tuning and driving around and this is the second tank of 87 octane I have run so fueling should be consistent. I am still running the ID725cc injectors and used to have E85 in it.

I am DONE WITH THIS SWAP! sort of. I just need to mount the ecu, cut my bracket and send you that present! Just tell me, are you still running the stock intake manifold Jeff?

I also need an IH8MUD logo. I suppose I can just copy one, off here, but better quality would be nice.

A/C is rockin cold...!

Wayne

 

[Texican]

I also need an IH8MUD logo. I suppose I can just copy one, off here, but better quality would be nice.



Wayne

I got plenty decals at the shop if ya want to drive to Bonham....

 

[rockrod]

Wayne - in regards to your question about the tow/haul mode. I asked Brendan with LT1swap.com that same question...

here's what he said:

You will use BLUE connector pin 71.
This is a momentary GROUND signal to TOGGLE between normal and performance or tow/haul mode.
Each new startup of the engine, it will default to Normal.
The PCM must be programmed to enable the use of this pin to switch modes.
-Brendan.

So supplying a momentary ground through a push button switch to pin 71 will turn on tow/haul, and then hitting it again will turn it off. Tow/haul will raise the shift points a bit, firm up the shifts, and also keep the trans out of OD for a longer period of time. It will also downshift the trans sooner as well. From what you posted earlier, it seems you may have already altered the shifting characteristics.

Have you removed torque management yet?

 

[wayneosan]

Yes, I have completely customized the tune, and if I could,I would have am input for tow haul or performance and have it be set up for crawling. That would be cool.

 

[warpdriv]

Glad to read the good news! Yes, i'm running the stock truck intake. I have no ABS since i'm running a 62 cases. So cruise is out for me. The tow/haul sounds cool though. I'm currently fighting P0220 and P2135 errors and have no throttle. I have put a new TB on and checked the voltage at all harness ground points. I plan on buying a new pedal, pedal harness, and TAC. Any thoughts?

Sent from my DroidCruiser

 

[rockrod]

where are you getting that not having abs means you can't have cruise? that's completely wrong.

all of the dbw pcms can do it you just need to send the correct signals through the correct wires. the toyota abs has nothing to do with it.

there is one wire connection to the pcm and 3 to the TAC module. While it's true you cannot use the toyota stalk unless you want to have a complex relay system to convert the negative grounding system to a positive 12v input.

 

[wayneosan]

Glad to read the good news! Yes, i'm running the stock truck intake. I have no ABS since i'm running a 62 cases. So cruise is out for me. The tow/haul sounds cool though. I'm currently fighting P0220 and P2135 errors and have no throttle. I have put a new TB on and checked the voltage at all harness ground points. I plan on buying a new pedal, pedal harness, and TAC. Any thoughts?

Sent from my DroidCruiser

That is common me thinks. I had this ALONG with the non linear matching app and tpp. So, it was tough to diagnose. I eventually just bought a brand new TAC module for the vin in my ecu. All is well, except the non linear pedals, which since I can scale them, I just scaled it. I just have not a lot of pedal travel. It's such an easy swap, that I figured I'd knock everything else out first and then do the pedal.

I feel that the throttle bodies don''t fail very often, and it's more likely that the TAC module has failed.

Another issue I have found is the female terminal crimps on these GM harnesses are really CRAPPY. A known issue is one on the MAP sensor. I have also found some on the pedal harnesses as well. I had to take a very slim pick and pry up the inside of the female prong to apply more tension on the male receptacle mating term. My MAP sensor ticked me off so bad that I also twisted the male terms in the sensor so that it applied more tension to the connections. No more hesitations.

?Try some harness repairs first on the connections then R&R the battery terminal to clear it all out, then test drive again.

wp

 

[warpdriv]

The connectors are the first thing I suspected. Eventhough my harness is new, I checked them anyway. All looks good. I'll pick up a TAC. Then if that does not work, a pedal and pedal harness.

 

[warpdriv]

Installed a new TAC. No luck. Still have P0220 and P2135. I went to clear the codes and they either will not clear or the computer is so fast, it puts them back in. I guess I need to get a pedal and a harness...

 

[warpdriv]

Well had a brain storm to try my old throttle pedal. No change. Not sure what's going here now.

 

[rockrod]

Have you tried another PCM just to make sure it's not the source?

How about the pedal to TAC harness? They are a known issue.

 

[warpdriv]

I do not have another pcm to try. I have another pedal that I tried but no success. I'm going to ohm out the harness from the pedal to the TAC see if there's any broken wires.

Sent from my DroidCruiser

 

[rockrod]

let us know what you find.

FWIW I just ordered a new tac harness and pedal for my rig. I currently have the 2006 and later plastic pedal and it's not a good fit in the 80. I ordered a metal 2005 and earlier pedal and tac harness from Jon at PSI. He said the harness is specific to the pedal, and the tac module is specific to the throttle body.