Removing NATS (Nissan Anti Theft System) from GU III 4.2TD Injector Pump

[davejones]

In May this year up in the high country I stopped for a lunch break and when I went to move the truck (GU Series 3 4.2 Turbo Diesel) forward to level ground it wouldn't start. Bit odd I thought, and then it started a couple of tries later and I put it down to altitude & forgot about it. (Well actually it niggled as I didn't believe my altitude theory and I wasn't sure what it was, and I hate that...)

Few days later it did it again. Being in mobile range this time I called a mate who works at a dealership and asked.

"Is the light on the dash on?" he asked.

I told him my Dynamco immobiliser was off. "Not that one. The one near the windscreen." he said.

My response "What light?"

Turns out there was a light that had been buried under dash mat and MSA dash organiser for years that I'd completely forgotten existed. A solid red light was on as he suspected.

Going through the manual override process in the moaners annual worked and that confirmed I had a NATS problem. A bit of diagnostic mucking around over the next month ensued, as there appeared to be a relationship between the Dynamco immobiliser and NATS problem. After a while I disconnected the Dynamco and the problem was still there so it was definitely a NATS issue.

I started researching NATS issues on this and other forums and found that I had what seemed to be an infrequently experienced problem.

There are a couple of modules involved in NATS. The one causing the problem was the CSOLU - coded solenoid on the back of the injector pump. Essentially this black box recognises a signal from the system telling it the right chipped key is trying to start the truck and it provides power to the fuel shut off solenoid. It's very conveniently (sarcasm) located on the top back side of the injector pump. I understand why for security purposes, but if this problem develops with your 4.2, and as with mine gets worse, and worse (ie. more frequent) it could leave you in strife in the middle of the Simpson or up in the high country, and the recovery cost if you didn't/couldn't fix it would be huge. Not great.

It's located here (blue):
diagram.jpg

I've seen a few posts about doing this on a few different forums now. Most involved bravery, long handled screw drivers and cold chisels, and belting the christ out of the little black epoxy thing until it's in a lot of pieces, while missing banjo fittings, injector lines and not damaging the pump itself. That wasn't going to be my preferred option. (There are pictures in a thread somewhere of a smashed CSOLU in bits.)

I called my mate Pete and asked if he wanted to come visit. He's a pretty handy mechanic and we've known each other a long time. He was up for a road trip. Turns out more than he thought as the hills got unseasonal October snow and he ended up doing a 900km trip to get the 450km here when he couldn't get over Hotham and had to return to the Hume and go the long way to Lakes Entrance.

While we were taking things out I decided to give the old girl a new radiator, water pump and hoses - particularly that little bastard under the inlet manifold.

We removed intercooler, radiator, fan, & water pump to get access to the front cover of the injector pump gears.

Pulling the battery and fuel filter out makes the next bits a lot easier.

Off with the inlet manifold, injector lines

Next it was off with the pump next to the injector pump. No timing issues to worry about on this one. There's a bolt/nut securing the injector pump that was impossible to get to without that pump coming off.

The harmonic balancer nut was too big for anything I or Pete had with us. Putting the truck in gear in 5th we moved it backwards until the injector pump timing gear ZZ & Z marks lined up, marked the top of the pump itself and adjacent mounting surface, so that when we put it back in it'd go back with the same pump timing.

Unplugging the wires on the pump (three connectors from memory, including the one hiding above the engine mount) the pump came out to the top side.

Keeping everything clean was important as you don't want to get grit or dust in lines going to injectors.

At this point we could finally get a good look at the culprit. The NATS CSOLU.

A couple of extracts found in another thread from the service manual show how it fits into the system.

Screen Shot 2014-11-08 at 2.11.43 pm.pngScreen Shot 2014-11-08 at 2.12.15 pm.png

I'd heard horror stories about the tamperproof bolts they use to put it on the pump. I was expecting an hour or so at this point to get the box off the pump.

Turned out with the right tools it was a 10 minute job.

A couple of months ago, one of the guys at the local tool joint BJ Bearings talked me into buying a couple of these -
Screen Shot 2014-11-08 at 2.18.03 pm.png

With the right bit chosen and the instructions read the following photos show the result:
prograbit in pump.JPGprograbit winding out tamperproof bolt.JPGprograbit with bolt.JPG

Once out the CSOLU was off in one piece. It's held on by a two piece clamp that locks around the body of the solenoid.

It was a simple matter after that to access the top of the solenoid by removing the clip on cap. Then you can undo the nut with an 8mm spanner and rewire the solenoid to direct 12 volt ignition switched power from the supply plug that originally fed the CSOLU.

I cut the plug off, extended the brown wire to a ring terminal and cable tied it to the pump brackets for strain relief. The pop on cap can be modified to fit a standard ring terminal. Bit of heat shrink and it was all good.
rewired.JPG

It's a bit of a process, and it's a lot easier to have two people to put the pump back in and get the timing marks right (ESSENTIAL) as its not a straight cut gear, but it went back together in an afternoon after the pump was out by lunch time.

Made me wish (again) that I'd put a pit in my shed when I built it!

Make sure when you put it back in that you don't miss the connector hiding on the bottom of the pump. The lead for it comes from the main harness at the same point as the oil pressure switch and the connector is nearly the same but black.

Last chapter to the saga was that when I put it all back together and started it the engine light was on. Forum posts had referred to taping over the light on the dash and I didn't know if they meant the engine light or the NATS light.

I took it into my dealer mate and the fault code was related to the injector pump timing. I started wondering if the CSOLU had another role as a pick up of some sort. "There's a metal plate in the side of it that could be a pick up..." I think out loud.


Don't need to do this bit.... just part of the story.
He was unable to find anything useful out from Nissan, so I thought if I wired the CSOLU back in, in parallel with the plug that's now powering the solenoid directly I could remount it on the pump. I spent most of yesterday doing that. Not as bad as the original job but still three fuel lines off, those mongrel fuel line clamps to deal with, battery out to get to all of it, contortion, a mirror and some 6mm allen head bolts to replace the anti-tamper ones and it was ready to test.

All that and there's still an engine light on in the dash. Grrr...

But I found a plug we'd missed plugging back in during all that process. I couldn't for the life of me see where it went, and it was clean inside so it had to have been somewhere for the last 10 years.

With Yendor's help on here this morning I learned that there's a mongrel plug you can't really see on the bottom of the injector pump above the engine mount. Once reconnected, no more engine light.

Long and the short of it, NATS is a pain in the arse. Nissan should never have put it in a spot that could see a vehicle disabled in remote terrain. It's something that if I bought another 4.2TD I'd immediately get rid of despite the days work involved.

Even if you had to pay a grand because you couldn't do it yourself, you'd potentially save a $5000 recovery from the Simpson.

Thanks to Yendor again for his help.

I hope this has been an interesting read, and it helps someone else.

Footnote: Alden Grabbit-Pro's should be in every man cave. You'll never use another EZ out again. They are awesome!

Cheers

Dave