eddybear44

I have a 2009 GX470 with 165,000 miles. The dreaded Christmas tree of lights would not go away for more than a day despite 2 new gas caps and the removal of the negative battery clamp for 30 minutes. The code reader gave me P0418-Relay Circuit Bank 1. The engine went into LIMP MODE so I decided to purchase the Hewitt SAIS Bypass. The tech at Hewitt was great and extremely helpful.

I began with the install of the block off plates under the vehicle. PB Blaster on the bolts for 2 days prior saved the day as it was like wrestling with a bear. You must be very careful not to strip the nuts especially on the drivers side. Use the smallest ratchet if you can and make sure it’s properly fitted. Once they were loosened it was easy to pry the connection open enough to slip in the bypass plates.

The bypass module itself was easy to install and the instructions and color pictures were excellent. Be SURE to.disconnect the neg terminal on the battery before starting. I threaded the 3 wire bundle into the removed glove box area with a metal coat hanger and electrical tape. My entry point was the small nipple on the passenger side firewall. It was hit and miss for 15 minutes but the wire finally emerged near the CD player.

The only difficult task was to strip insulation from wires on the existing plug without cutting them. I then wrapped the 3 Hewitt wires and then soldered and wrapped them. I would not use the enclosed Scotchlok connectors as they look flimsy and don’t make a solid splice. Make sure to triple check each wire and it’s location on the plug. The Hewitt instructions were great and while I am not at all mechanically inclined this is a straightforward job most anyone can do. The SUV drives perfectly with no engine check lights and no limp mode. Best $400 I ever spent.

NTH

Why did you have to run your wires through the firewall? And to connect to what? I thought all connections were in the engine bay.

eddybear44

I installed the Hewitt Generation 2 Three Valve unit which is an improved design over the one featured in the Hewitt YouTube videos. It eliminates the single purple wire to the fuse box. A bit more work but more comprehensive.

eddybear44

Look up the instructions on the Hewitt Tech site and it explains the process.

NTH

Ahh ok.
Another option to go through the firewall is the AC drain grommet.

eddybear44

Yes, there are several firewall options. The Hewitt website shows several entry points and does an excellent job of guiding you thru the process which is why I recommend this fix to anyone having the issues I had. This latest generation bypass is definitely a new and much improved solution.