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A BUNCH of extra ECU crap about 3.5 swapping ... you will probably never need it

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A BUNCH of extra ECU crap about 3.5 swapping ... you will probably never need it

Old 08-21-2006, 04:32 AM
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Originally Posted by nismology
Another thing i was confused about.....the A32 guage cluster recieves the VSS signal at terminals 2 and 4 from VSS terminals 1 and 2. The A32 ECU recieves the VSS signal directly to pin 29. My question is this...how can the signal get to three difference places if there are only 2 terminals on the VSS? I need to know so i can figure out how to get the signal to all three places. Thanks in advance.
A32 - ecu pin 29 is connected to gauge cluster pin 24
- gauge cluster is connected to VSS on 2 and 4

The VSS is not directly connected to the ecu
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Old 08-21-2006, 08:06 AM
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Originally Posted by eng92
A32 - ecu pin 29 is connected to gauge cluster pin 24
- gauge cluster is connected to VSS on 2 and 4

The VSS is not directly connected to the ecu
Awesome. Thanks as always. Now with this said, is there any way i can multiply the frequency of the signal by a factor of four like the A33B gauge cluster would or would the ECU be satisfied with a low reading? I know a speed limiter would never be a problem with a low reading, but i'm just wondering if other things like ignition timing and/or VTC timing would be affected.

Sorry for all the questions. I just want to get it done right the first time...
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Old 08-21-2006, 08:34 AM
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Originally Posted by nismology
Awesome. Thanks as always. Now with this said, is there any way i can multiply the frequency of the signal by a factor of four like the A33B gauge cluster would or would the ECU be satisfied with a low reading?
I am afraid you are the pioneer on this one.

I never had any codes for speed "out of range". The ecu wouldn't spit any data out for indicated speeds >240 km/hr (~149 mph) which I would hit at an actual speed of ~ 60 km/hr (~37 mph).

Give me a couple of days and I will put the scope on the VSS input and output for the gauge cluster. Then we can definitively see the difference in voltage and frequency between the two signals.
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Old 08-21-2006, 08:42 AM
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Originally Posted by nismology
I know a speed limiter would never be a problem with a low reading, but i'm just wondering if other things like ignition timing and/or VTC timing would be affected.

Sorry for all the questions. I just want to get it done right the first time...
With a 5MT, the ecu has no idea what gear you are in. I have done WOT runs in several diffferent gears and never observed any appreciable change in either of those parameters.
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Old 08-21-2006, 09:25 AM
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Based on your first-hand experience, i might just leave it alone. Now if i could only manage to get my hands on a blasted main harness....
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Old 08-21-2006, 11:41 AM
  #46  
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Originally Posted by nismology
Now if i could only manage to get my hands on a blasted main harness....
Yes, dash harnesses can be pretty hard to come by. A lot of wreckers do not even bother removing them as there is so much labor involved and just a single stretched wire can render them useless.

Up here in Canada they are really hard to come by. It took me over 2 months to find one. Then when I received it, the connector for the immobilizer was cut off. I had to make one out of another connector, some epoxy and some spare female terminals I had.
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Old 08-21-2006, 12:45 PM
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Originally Posted by eng92
Yes, dash harnesses can be pretty hard to come by. A lot of wreckers do not even bother removing them as there is so much labor involved and just a single stretched wire can render them useless.

Up here in Canada they are really hard to come by. It took me over 2 months to find one. Then when I received it, the connector for the immobilizer was cut off. I had to make one out of another connector, some epoxy and some spare female terminals I had.
Yea none of the local bone yards seem to even have a wrecked A33B, let alone a dash harness.

I'm putting in a nationwide request for one through junkyarddog.com. Does it matter which transmission the car had or will either one work?
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Old 08-21-2006, 01:16 PM
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Originally Posted by nismology
Does it matter which transmission the car had or will either one work?
No, both my main and engine harnesses came out of autos. 6MTs are a pretty rare breed up here. You discard everything that differentiates them anyways so it does not matter.
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Old 08-21-2006, 01:18 PM
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I spoke too soon. I didn't notice car-part.com was able to search for wiring until now.

Found a few dash harnesses, albeit not local. How exciting!! I'll let you know when i recieve one and start trimming it down.
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Old 08-21-2006, 01:33 PM
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Originally Posted by eng92
No, both my main and engine harnesses came out of autos. 6MTs are a pretty rare breed up here. You discard everything that differentiates them anyways so it does not matter.
Awesome. Good to know.
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Old 08-22-2006, 03:24 AM
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You will also need to replace the A32 power steering pressure switch with the A33B pressure sensor to avoid getting a P0550 code. It is a direct swap and the connector for it is on the engine harness.
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Old 08-23-2006, 06:18 PM
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Thanks for sending me the huge pix of the harness. I really appreciate it.

Which wires are connector M81 on the adapter harness wired to? And is the 16 pin connector an original A33B main harness connector or did you get it from somewhere else? Thanks in advance.

And i'm not sure exactly how i'd go about adding the two fuses.
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Old 08-23-2006, 09:01 PM
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Originally Posted by nismology
Thanks for sending me the huge pix of the harness. I really appreciate it..
No problem. I will send a few of the wire routing in the engine bay when I get a chance.

Originally Posted by nismology
Which wires are connector M81 on the adapter harness wired to?
M81 is the designation for one of the stock A33B main harness connectors that plugs straight into F49 on the A33B engine harness. On the picture I sent, I specified that it was not the original connector because I had to replace it with another one that I had. It was another connector that was missing when I received the main harness from the wrecker. I didn't want the brown color to confuse you because the stock one is white.


Originally Posted by nismology
And is the 16 pin connector an original A33B main harness connector or did you get it from somewhere else? Thanks in advance.
I had some extra A32 main and engine harnesses kicking around so I used some of the mating connectors from them.

Originally Posted by nismology
And i'm not sure exactly how i'd go about adding the two fuses.
I just used a couple of weathertight inline automotive fuse holders. For power to them, I tapped into the lead coming off the 75A fusible link in the under hood fuse box.
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Old 10-24-2006, 03:12 PM
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How did you manage to retain the immobilizer feature? I thought of just taping the key to the NATS IMMU but that kinda defeats the purpose.
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Old 10-24-2006, 03:51 PM
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You could always go the ghetto way ... keep 2 keys in the pocket . Just kidding. Someone needs to find a way to stuff the 5th gen ignition equipment in the A32 steering column.

This sounds really stupid, but why exactly doesn't it fit? The immoblizer just bulky enough to screw it up?
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Old 01-31-2007, 02:06 PM
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I figured since this question has to do with full 3.5 swapping I might as well throw it in my thread.

What is up with the Refrigerant Pressure Sensor? I asked Nismo last night, but unfortunately I got disconnected so I am not sure I got his full answer.

Obviously it is intended to messure the pressure of the refrigerant in the a/c system. Why is it that the A32 lacks this sensor? If a full A33B swap was being performed, would the A33B A/C system have to be used or could the sensor be fit in the A32 system?

Is it the case that it is just named something else in the A32 FSM?
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Old 01-31-2007, 02:33 PM
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Wow ... I just found the simularities. The A32 Triple Pressure Switch is an A/C exclusive component.

The A33B Refigerant Pressure Sensor is an ECU and A/C component. Fortunately the ranges of low and high pressure tolerances are close enough in the A32 sensor. The problem is we need to figure out exactly which voltages are released in which cases. If it is possible to splice the data wire from the triple pressure switch into the A33B ECU harness then by all means it should be done.

Anyone know where some of this info can be found? I think the A32 system is a relay system versus the voltage system of the A33B.

People please comment on this or make suggestions about how we can go about connecting this stuff up. All of this will lead to less painful full 3.5 swaps ... especially codeless/CEL-less 3.5 swaps.
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Old 01-31-2007, 05:30 PM
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Originally Posted by scrhale
All of this will lead to less painful full 3.5 swaps ... especially codeless/CEL-less 3.5 swaps.
There are no codes associated with the refrigerant pressure sensor or lack thereof.



Three straightforward solutions immediately come to mind. The correct choice depends upon your requirements and level of ingenuity.

1) The $0 do nothing solution - leave the ecu independent of the a/c system.
Two ill effects -
i) the ecu does not automatically raise the idle rpm when the a/c is on
ii) the ecu does not automatically turn off the compressor at high engine speeds or large throttle openings


2) The full featured, possibly expensive solution - Plumb the A33B pressure sensor into the system.
Of course now you will need to have your system evacuated and recharged again.

EDIT: this is really not that feasible of a solution as the A33B sensor needs to be plumbed into the condensor.


3) The cheap, ingenious solution - a couple of relays and some resistors can be used to feed the ecu a pressure sensor voltage in the appropriate range.
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Old 01-31-2007, 08:10 PM
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Which option did you go with?


Apparently, the A33B uses info from this sensor in conjunction with coolant temp sensor info to determine when to turn the fans on. This is just from a quick glance in the FSM.
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Old 02-01-2007, 06:33 AM
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I think I see what you are saying eng92 about the resistors and relays.

Another problem ... Fuel Level Sensor Unit.

The A32 equipment ranges are pretty close to the A33B ranges, but don't quite make it all. I think the differences are because of different dimensions in fuel tanks.

Please check out EL-79 in the A32 and EL-129 in the A33B and we'll see if we can just leave and tap into the A32 equipment.

LOL ... I guess we can all prepare for when I ask about how the VSS should be hooked up if 5Spd or 6Spd is used. I think that is my last question surprisingly.
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Old 02-01-2007, 07:41 PM
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Originally Posted by nismology
Which option did you go with?
A combination of options 1 and 3.

I just replaced the A33B pressure sensor with two 1K 1/4 watt resistors.

This supplies a constant 2.5V to ecu pin 81 which keeps it happy. Meaning it will provide a ground for the ac relay on pin 21 when called upon. The compressor will still be protected from extreme high and low pressures by the stock triple pressure switch which will open the circuit.

The only thing I still need to do is add a relay to perform the a/c cut function. The A33B conveniently provides a ground on pin 30 to make this possible.
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Old 02-01-2007, 08:07 PM
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Originally Posted by scrhale
Another problem ... Fuel Level Sensor Unit.

The A32 equipment ranges are pretty close to the A33B ranges, but don't quite make it all. I think the differences are because of different dimensions in fuel tanks.
The ecu does not care how much fuel you have in your tank. The absolute voltage reading does not matter. The only reason for the ecu connection is to see if the voltage fluctuates at a vehicle speed of zero which would indicate a sending unit malfunction.


Originally Posted by scrhale
LOL ... I guess we can all prepare for when I ask about how the VSS should be hooked up if 5Spd or 6Spd is used. I think that is my last question surprisingly.
The 5spd VSS wiring has previously been covered.

The 6spd VSS wiring will require a little more thought.

Just shooting from the hip:
1) If you have ABS, you may be able to derive a vehicle speed signal from the controller.

2) I believe there is a speedometer gear on the final drive in the 6 speed tranny but on the A33B I do not think there is a hole in the casing to actually mount the sensor. Perhaps a 6-speed fwd tranny out of something else like a Sentra might have one and all you have to do is swap bellhousings.
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Old 08-01-2007, 02:26 PM
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This thread has been incredibly helpful with my swap as all the stuff related to using the A33B i have come across or yet to come across, including but not limited to the power steering switch, relay and fuse for the throttle motor, the F49 connector on the engine harness which is the only harnesss to plug in direct even though it has extra wires for the APP sensor, and stuff yet to come.

Using back the I35 instrument cluster and gear shifter also, so not sure what "problems" may come up. Used back the PNP switch from my VQ20 as the one on the VQ35 tranny was broken. Now sure if it would work...
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Old 05-22-2017, 11:42 PM
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anyone still here?
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Old 05-30-2017, 08:03 PM
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Yea...
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