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Fix for Gen3 Cruise Control and AC

24K views 140 replies 26 participants last post by  David Hawkins 
#1 · (Edited)
Ok, I just completed a swap on a 93T to install a Gen3 motor on a customer's car (my first Gen3 swap) and got the AC and Cruise Control working as normal. I know this will be different on the 91T, but it should be fairly similar.

The Cruise Control:

The sympoms: The speedo didn't work at first, but we ran an auxiliary ground to the brown wire in the white connector that ran to the body harness to get it working. At that point the cruise would turn on, then it would shut off after engaging momentarily, flash the light on the dash, then not turn back on until the ignition was turned off, then back on.

The solutions: The differences we found were that the Pink wire in IE4 is missing that taps into the "IDL" wire off of the TPS (pin 2). So for that we ran a wire to the kick panel and inserted a pin into IE4 12 (which I sourced from one of the gen3 tail light connectors). We also had to replace the TPS sensor for some reason, but I'm not sure if it was just bad, or what as the car ran fine with it, but replacing it with the gen2 TPS seemed to work. After this, the cruise worked fine.

The Air Conditioning (AC A/C):

The symptoms: The AC light turns on on the dash, but doesn't do anything -- the AC magnetic clutch isn't engaging.

The solutions: Aparently the Gen3 runs the AC in a similar manner to the NA as it uses a pink/green wire in IE3 to trigger the AC amplifier as to when it's supposed to turn on the AC compressor. We found this wire present, and the car seemed to be wired on the kick panel for this wire also, but the gen2 harness we removed didn't have this wire. So we cut this wire. We also found that there was supposed to be a tach signal from the ignitor going to the AC amplifier on IE4 pin 10. This was also an empty pin on the wiring harness for the Gen 3 -- so we inserted another pin, and wired it to splice in to the IE1 connector's tach signal to the dash.

The other wires missing on the gen 3 harness appear to be the idle up wiring for the idle up VSV -- but I believe as long as the gen3 ecu is getting the signal that the AC is on (black/white wire) it is controlling the idle up VSV as that appeared to be what was happening.

I hope this helps some people out there with 3rd Gen swaps.

PS -- to turn off the oil level light, some have said to unplug the oil level ecu, but unfortunately the 93+ cars don't have an oil level ECU. So we wired the blue/white wire on the BM1 connector (gen 2 side of the harness or red on gen 3 side of harness) to ground, and the light went out.
 
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#2 ·
sorry to bring this back , but do you know if the tps is different (signal wise)? I looked at my gen2 and gen3 and on the outside they look different, it looks like the connector plug is the same, did you just swap it in? also where did you get the signal from? did you just splice the wire before it goes to the ecu? thanks
 
#3 ·
Hmmm, I wonder if I have this problem. I had my motor swapped in October and some things that were "said" to be done/ok were not.

I have a 91 NA chassis and a 98 3s put in. Both my cruise and AC dont work. My cruise light comes on, but does nothing. My AC light comes on, but does not clutch.

Is there some kind of DVM testing that can be done at the connector to see if its used or not (in reference to the pink/green wire at IE3)? Id rather not just cut the wire to see if it works.

Shame I have to trouble shoot someone elses work when it was promised to work correctly. *shakes head*
 
#6 ·
redmk2 said:
sorry to bring this back , but do you know if the tps is different (signal wise)? I looked at my gen2 and gen3 and on the outside they look different, it looks like the connector plug is the same, did you just swap it in? also where did you get the signal from? did you just splice the wire before it goes to the ecu? thanks
I swapped the Gen2 TPS onto the Gen3 thinking it was the problem at one point and it plugged in just fine. I've also got the Cruise working on other cars without running the wire to the TPS pin 2 -- so I'm not sure what was going on with this particular car. I tapped into the wire from the TPS in the trunk where it goes to the ECU.

Colonel said:
Hmmm, I wonder if I have this problem. I had my motor swapped in October and some things that were "said" to be done/ok were not.

I have a 91 NA chassis and a 98 3s put in. Both my cruise and AC dont work. My cruise light comes on, but does nothing. My AC light comes on, but does not clutch.

Is there some kind of DVM testing that can be done at the connector to see if its used or not (in reference to the pink/green wire at IE3)? Id rather not just cut the wire to see if it works.

Shame I have to trouble shoot someone elses work when it was promised to work correctly. *shakes head*
For the Cruise on the 91, you'll need to make sure the CC speed sensor is installed (some people don't put this back for some reason) in line between the speedo cable and the transmission. You'll need to wire the CC speed sensor to the 93+ style speed sensor connection. If I remember right, the colors are as follows in this format: Engine harness color goes to sensor wire color: Black/yellow stripe goes to pink (or red), white/black stripe or Brown goes to black, violet/white stripe goes to yellow.

If you wanted to disassemble the IE3 connector with the pink/green wire, you could de-pin it -- but it's a bit of a hassle as that connector is 3 rows tall and the retainer has to pass through all 3 levels straight (a bit tricky). I've got 3 different gen3 cars' AC to work doing this same thing, so I'm pretty confident in the cure. Run the tach signal wire, and then cut the pink/green and it should work like a charm. If you check your NA harness, it does use the pink/green wire, but the gen2 turbos do not -- and basically what we are doing is making it run the AC amplifier like a gen2 turbo car. When the pink/green wire is there, it is looking for the ECU to trigger the amplifier, and something I'm not aware of is missing in the equation for it to work with the pink/green wire.
 
#7 ·
Loki said:
I swapped the Gen2 TPS onto the Gen3 thinking it was the problem at one point and it plugged in just fine. I've also got the Cruise working on other cars without running the wire to the TPS pin 2 -- so I'm not sure what was going on with this particular car. I tapped into the wire from the TPS in the trunk where it goes to the ECU.
ok so you are saying on other cars you DIDNT run the IDL signal from the tps to IE4 and the cruise control still worked? B/c on a 91, the only things that i can see coming from the engine bay to the cruise control system is the speed signal (which i already have) and the IDL which I"m missing and was gonna try wiring tonight.

what was the circumstances that you got the other cars running without running the wire to tps pin2? did they have cut harnesses that you had to solder b/c the only other people i know of that got gen3 with cruise control working was b/c they had cut harnesses and had to solder two halves of a 91 harness and a gen3 harness together.
 
#8 ·
redmk2 said:
ok so you are saying on other cars you DIDNT run the IDL signal from the tps to IE4 and the cruise control still worked? B/c on a 91, the only things that i can see coming from the engine bay to the cruise control system is the speed signal (which i already have) and the IDL which I"m missing and was gonna try wiring tonight.

what was the circumstances that you got the other cars running without running the wire to tps pin2? did they have cut harnesses that you had to solder b/c the only other people i know of that got gen3 with cruise control working was b/c they had cut harnesses and had to solder two halves of a 91 harness and a gen3 harness together.
I should qualify that the other cars I've not had to run the IDL wire on were 93+ cars so the wiring was a little more similar to Gen3. They weren't cut harnesses -- the gen3 harnesses were complete.
 
#10 ·
Loki said:
For the Cruise on the 91, you'll need to make sure the CC speed sensor is installed (some people don't put this back for some reason) in line between the speedo cable and the transmission.
I hope for the sake of the installer this was done. If not there is going to be some serious issues.

Loki said:
You'll need to wire the CC speed sensor to the 93+ style speed sensor connection. If I remember right, the colors are as follows in this format: Engine harness color goes to sensor wire color: Black/yellow stripe goes to pink (or red), white/black stripe or Brown goes to black, violet/white stripe goes to yellow.
I have a mechanical speedometer (91NA) but have the electronic sensor that goes with it. In "theory" I am ok given the explaination above? Id still research the colors, but if I have that electronic to mechanical sensor, I should be good to go...given that above inline sensor described above is there?

Loki said:
If you wanted to disassemble the IE3 connector with the pink/green wire, you could de-pin it -- but it's a bit of a hassle as that connector is 3 rows tall and the retainer has to pass through all 3 levels straight (a bit tricky). I've got 3 different gen3 cars' AC to work doing this same thing, so I'm pretty confident in the cure. Run the tach signal wire, and then cut the pink/green and it should work like a charm. If you check your NA harness, it does use the pink/green wire, but the gen2 turbos do not -- and basically what we are doing is making it run the AC amplifier like a gen2 turbo car. When the pink/green wire is there, it is looking for the ECU to trigger the amplifier, and something I'm not aware of is missing in the equation for it to work with the pink/green wire.
To understand this, you have to run a tach wire to get teh AC to properly function? *scratches head* How bizzare! Any idea what the tach signal does for the AC system?

Looks like after vacation I got to clean up even more work. Wow, pay a premium price and I still end up doing the work. :rolleyes:
 
#15 · (Edited)
Colonel said:
I have a mechanical speedometer (91NA) but have the electronic sensor that goes with it. In "theory" I am ok given the explaination above? Id still research the colors, but if I have that electronic to mechanical sensor, I should be good to go...given that above inline sensor described above is there?

To understand this, you have to run a tach wire to get teh AC to properly function? *scratches head* How bizzare! Any idea what the tach signal does for the AC system?
You should be ok if the wiring is hooked up to the 91 CC speed sensor -- you'll have to make sure that sensor ground is present -- it often isn't, even on 93+ cars that I've swapped gen3's into. Check the ground wire running on the white connector in the rear trunk that goes from the engine harness to the body side harness -- it should be the only ground wire in that connector. If it's not going to ground, then your speed sensor isn't grounded. The easy fix is to run a wire between that wire and the starter relay ground wire.

The tach signal to the AC is to prevent the AC compressor from overrunning as RPM's rise (I would guess) and burning the compressor out.
 
#16 ·
Thanks for the info, Kris. *subscribed* in hopes that someday I'll catch up on my grad school homework and find time to play with my swap to get the A/C working. (oh, I have to buy a compressor too and who knows what else, but its really REALLY nice to have helpful info like this for that someday).

Geoff
 
#18 ·
TTE said:
Is power steering working after swap. My doesn't and I don't know where to look for lost signal. I also have 93T with 3gen engine
I posted something a while ago on how to make that work, I also have the instructions written up in my self made Gen 3 book. Give me a sec....

From Here: http://www.mr2oc.com/showthread.php?t=188481&highlight=Body+Harness

ward spose said:
.....
Here are the definitions I was given for reference as to which plug is which, so we are all communicating in the same language. All plugs go to ECU unless other wise noted. All Pin Numbers are with the Terminals Facing You.

Plug "E4" = 22 pin Connector (Grey)
Plug "E6" = 26 Pin Connector
Plug "EA1" = 15 Pin Connector (to Body harness) (White)

Here is What I have so far and beleive to be correct:

1) Powersteering (1) - E4 Pin 8 (Black wire) swap to Pin 18 (blank)

2) Powersteering (2) - E4 Pin 7 (light Blue/Yel stripe) Swap to Pin 8 (now Blank from #1)
...
That should take care of that for you.
 
#23 ·
just want to say thanks to loki for the help. my CC hasn't functioned since november when the 3rd gen swap was done...i've tried hooking the wires togehter like pat signorino's site suggested and it didn't work, then i found this thread, put the sensor wires together as stated and it still wouldn't work. So with some help, i found the ground wires, ran a small speaker wire from the brown to white/black stripe wire in starter relay and BAM!!! i have working cruise control.

<-- stoked
 
#26 ·
notbob said:
i did a 91t to gen3 swap, where are those connectors at for fixing the a/c?

any chance of some pics of what you had to do, i've been debating ripping my a/c out but if i could fix the wiring on it i'd be super happy
The connectors for fixing the AC are in the driver's side kick panel area and involve 3 of the connectors on the body harness that runs to the back of the car.
 
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