Anyone rewired a rev sensor in a GQ automatic?

[ripper]

Our auto was giving trouble, and based on what an auto trans specialist said I decided to replace it. Finally the swap is almost finished, but I have an issue with the rev sensor. I can't use our original rev sensor because the new housing is cast slightly differently, and our old one wont fit.

The cable to the rev sensor has a wound coax type layer and three strands inside, two insulated, and one bare. Does anyone know if I can just cut the old wires and join them to the new ones? or is the cable calibrated to a certain length/resistance, or something complex like that?

Thanks.

[YNOT]

Don't take this as gospel as I don't know for sure, but I wouldn't have thought the wires were tuned length so joining "should" be OK. You would need to cover the join with the coax which is there as a shield against electrical interference.
The best thing to do would be to get the correct sensor for the housing.

Tony

[ripper]

Thanks Tony, I didn't know why it was wrapped in coax, so that's good.
I've got the correct sensor for the housing, it just doesn't have a connector on the end of it's cable. I must've explained that part badly.

[YNOT]

Are the pins inside the connectors the same size and shape? If they are you should be able to back them out of the connectors and swap them over.

Tony

[ripper]

The new cable doesn't have any pins on it. I haven't actually traced where the old cable plugs in, I just figured I'd cut it and join the new one on. Then I noticed what type of cable it is and freaked a bit.

[YNOT]

If the original sensor won't fit and the sensor that came with the reco trans has no plug then you've got nothing to really lose by trying to splice the connector on.

Tony

[Yendor]

I agree with Tony it is only a hall effect sensor, so changing the length or resistance of the harness should not affect it's operation.

[ripper]

Thanks for that, I just didn't want to make some dumb mistake with it.
No point cutting into the old one if there was no chance of it making the new one work.

[ripper]

Well I never got to test if my rewiring of the rev sensor worked, because it turned out the box had other massive problems.

I hope the saga of our automatic is finally over.

I'll share the whole sad story here now, in case it's of use to someone else.

When we bought our GQ with less than 250k on the clock, the auto worked perfectly. After a few thousand km it started to play up. The torque converter lock up would cut in properly, but drop out again a few seconds later.

The ATF was slightly burnt, so I decided to get it serviced. Riverina Automatic Transmissions in Griffith said they'd service it for $250. When they opened it up they said there was so much rubbish in it that it wasn't worth servicing. Instead of the $250 for a service, they charged $50 for their labour and the ATF to get it running again. At this stage they offered to reco it, or if I bought a second hand one they could remove ours and fit the new one.

I decide to go with buying a second hand one, and because funds were short, to fit it myself. My father has a hoist, and was keen to help too. Found a box on ebay, and the seller said he got it for a project but discovered it was too big. He sent me some photos of the inside of it, and it was all nice and clean, so I thought it would be good.

Fitting the box was fine, until I found the housing that bolts to the transfer case was about 12mm shorter than the old one, and the output shaft was also different. This wasn't a big deal, as the auto came with a transfer case. Also this shorter case was the reason the rev sensor needed rewiring, which prompted this thread.

The first sign of real trouble with this box was after I'd gotten it all in and connected up, and as I changed it's filter, a piece of metal about 10mm square fell out of it. I was still optimistic, but my father was more realistic (and experienced). Filled it with ATF, started it up, and it did absolutely nothing. Dad suspected the piece of metal from the filter was a vein from the pump, and it turned out he was right.

I rang the guys at Riverina Auto and they said they'd said they see if they could build me one good box out of the two. So I took both boxes to them. When they rang back it was more bad news. The box I'd bought was totally useless, so I bit the bullet and told them to reco the original box.

So now I had our Trol with no transmission in it, and the Auto shop 50 K's away. Now there were two choices, a tilt tray to take the Patrol to Griffith, or to fit the reco'd box myself. Still trying to keep costs down, I decided to fit it myself. In it went (I was sick of doing this, but was getting faster at it), I fired it up, and drove it off the hoist. All went well, till I put it in reverse. No go.

Rang Riverina autos again, and they said to bring it straight over. They hoped it was just a stuck solenoid. They were wrong though. It turned out a seal in the reco kit was faulty, and was letting the ATF bypass the reverse section of the transmission. They had to pull the box out and strip it down again to replace the seal.

Drove home and it worked like a dream. Stayed like that for a few weeks, then a new problem started. It would randomly loose 1st and 4th gear. Back to Riverina autos it went.

It drove them crazy. They replaced the valve body, they replaced the computer, they tested and replaced every thing they could. They rang me one day (after a couple of weeks) and said it was fixed, and I could collect it when ever I wanted. They rang me back a couple of hours later and said it had started playing up again. During this time (weeks) I had their 80 series Cruiser as a loaner. In the end they said they couldn't come up with any other possible solutions. All they were sure of was that it was definitely electrical, not mechanical or hydraulic. They suggested I take it to an auto electrician. It didn't sound like warranty work, so I offered to pay them for the time and parts they'd used, but they wouldn't take anything because they hadn't been able to fix it. I talked to our local sparky about it, and he said he sent any trans problems to the trans guys, and if they couldn't fix it, there's no way he could.

As you can imagine, things now looked pretty grim. I studied up the workshop manual, fiddled with with the Trol till it finally gave me a flash code error. This was what had messed the auto guys around, it wouldn't play up for long enough to give them a code. The code I got fitted with where they thought the problem was. One solenoid controls 1st and 4th gear, but they'd replaced the solenoid when they replaced the valve body, and that hadn't fixed it. From here on I just followed the trouble shooting guide from the manual, and found the problem. A wire in the main transmission harness was meant to have 20-30ohms resistance, but it wasn't conducting at all. Got Riverina Automatics to replace the main harness and that fixed it.

So far so good. Hopefully it doesn't have any more nasty surprises. I've had enough.

TL;DR
We had auto trouble. Bought a second hand box but it was no good either. Got our original reco'd but a broken wire in the main harness caused random problems and frustrations with it for months.

[NissanGQ4.2]

Great write up ripper......did you get a refund on the box you bought off ebay????

[taslucas]

Cheers for the info. By process of elimination, I think my problem is also electrical.

tappn it

[ripper]

did you get a refund on the box you bought off ebay????

No, the guy sounded genuine. He was a bit unsure when I asked him to take the sump off to photograph the inside of it for me, he was worried about wrecking the gasket on it. I don't think he did anything wrong, and would've had the same problem I did, if he'd used it in his project.


Cheers for the info. By process of elimination, I think my problem is also electrical.

tappn it

Sounds like it. Now comes the challenge of narrowing down which electrical component.

Mine was really frustrating, but once I got that error code, and followed Nissan's troubleshooting process, it all worked out.

[taslucas]

The box changes perfectly(way better than standard with the aftermarket valvebody). I have all gears etc. It's just the lockup TC that drops in and out at 90 to 100 km/h. And only when its really warmed up (after 20/30 mins of driving) so hopefully it has to do with the temp sensor.
Another strange thing is if I get straight onto the highway I can drive for over an hour at 90/110 km/h and it won't play up. But if I drive around country roads it starts to play up after 20 mins or so ?



tappn it

[Bigrig]

Top write up old mate!!

[ripper]

It's just the lockup TC that drops in and out at 90 to 100 km/h. And only when its really warmed up (after 20/30 mins of driving) so hopefully it has to do with the temp sensor.

Hopefully you're right.
That was the first problem with ours. Since the box was reco'd, it hasn't done that at all.
No idea what was causing ours to do that before, but Nissan's guide in their service manual was what fixed ours in the end.

[taslucas]

Hopefully you're right.
That was the first problem with ours. Since the box was reco'd, it hasn't done that at all.
No idea what was causing ours to do that before, but Nissan's guide in their service manual was what fixed ours in the end.

The most common cause of the TC lockup dropping in and out is a worn out TC.
95% a reco TC fixes it (if the box is still in good condition)

tappn it