The GMPP controller kit and the Infinity system both combine to provide everything the vehicle and engine needs to operate seamlessly together. I’m not much of an electronics or wiring guy so I was a bit hesitant to jump into this task. The GMPP harness is fairly straightforward – well identified harnesses that plug into their respective sensors for the most part. If you don’t know where a sensor is a quick google search pulls up plenty of photos. The GMPP harness can be routed and installed in about an hour – assuming you don’t make many changes …
I really struggled to position and install the GMPP fuse box. There’s one obvious attachment point on the exterior of the box but I didn’t think that would be secure enough. After poking around for longer than I care to admit I figured out how to crack the box apart so I could bolt it directly to the chassis – much more secure!
Ken warned me not to place the ECM buried so deep behind the spider but I really didn’t want to put this on the firewall. I was originally saving space on the firewall for the surge tank but I ended up finding an alternate location for the tank. I’ve seen several builders screw these right into the side of the chassis; I used a 1″ OD / 1/4″ ID piece of rubber tube to push the ECM off the chassis and give it some small amount of vibration isolation.
By pulling apart the entire GMPP wiring harness I was able to free enough of the Drive By Wire (DBW) harness to bring it forward into the pedal box area without the need to splice in an extension or run an extender harness. I was very wary of messing with the factory DBW wiring at all as I’m unsure if modifying this may lead to drivability issues later down the road.
I elected to replace the dash unit supplied in the kit (the KOSO display) with the MXS Strada from AIM. I just didn’t like the aesthetics of the KOSO unit despite it being perfectly capable (and fully integrated with the Infinity system). The Strada is a stripped down version of their MXS datalogging system. It’s got the same display capabilities and none of the data logging. For a street car, this is more than adequate. I plan to install a Dakota Digital GPS receiver as reports from other builders have suggested stalling issues were eliminated by connecting one of these to the ECU’s vehicle speed sensor (VSS) harness. I figured since I had a speed signal from the ECU I would just pull this from the CAN system and feed this directly into my AIM unit. I’ve heard from others that the AIM system is not able to pull vehicle speed from the CAN system and therefore I will need to purchase the AIM specific GPS sensor to get a speed readout on the display. It also seems the DD GPS can’t talk to the AIM dash and the AIM GPS can’t talk to the VSS. NUTS.
I’ve just gotten the AIM dash unit fired up for the first time so I’m playing with this to see if I can get it to pull vehicle speed from the Dakota Digital GPS unit by way of the GM ECM before plunking down for the expensive AIM GPS sensor. Seems silly to be running 2 GPS systems to get vehicle speed. I’ll report back with my eventual findings.
To read oil temperature I purchased the PT100 thermoresistor w/ 1/8″ NPT sensor from AIM and installed it into an Improved Racing (PN EGM-106) oil cooler adapter. It has pre-tapped 1/8″ NPT ports for oil IN and oil OUT (from and to cooler). Installing the temperature sensor in the oil OUT port will give a better reading for how hot the oil temp is running. A 719 binder extension cable is helpful for getting the oil temperature sensor cable up into the passenger compartment – if you go with the MXS Strada you’ll have to cut the pre-terminated wire apart to convert it to flying leads. The full MXS system has pre-terminated 719 connectors so it’s simply plug-n-play.
One additional benefit of pulling the GMPP harnessing apart is I was able to pull my CAN+ and CAN- wires from the harness and run them up into my dash area, again without the need for extensions. The CAN wires are twisted throughout to shield against external electrical interference. I had originally thought about using the pre-wired rear-to-front signal wires provided by the Infinity system, however once I discovered the CAN wires were twisted (and the Infinity wires are not) I felt running the original GMPP wires up to the front to be the best solution.
At first, everything went fairly smoothly with installation of the Infinity system…
Then I got into trying to integrate the GMPP and Infinity systems and that’s where things go awry. Infinity systems has a helpful blog post that talks about how to integrate the two systems here. So I was able to figure out how to physically link the two and wire it all up but where I started scratching my head was in wondering what benefit the system was truly providing for me. My use of an alternate dash system and a separate stand-alone alarm knock out 2 of the biggest advantages of the Infinity system; namely full integration of the dash and a built-in vehicle immobilizer. I don’t intend to take advantage of the additional accessories/expansion modules offered by Infinity.
In essence the Infinity system Master Cell (MC) acts as the brains of the car and everything else reports to, and is controlled by, the MC.
However, why would I want to have the MC control my fuel pumps when:
- The supplied wire gage appears to be either 16 or 18 with a fusible link(?).
- I need to purchase an inVERT module or install an additional relay and wiring.
- It’s just one more thing to malfunction which may result in an engine no-start condition.
Other things which bother me about the Infinity system:
- (Likely) insufficient wire gage for radiator fans.
- Wiring provided for the Ramlift motor is 16 AWG whereas the wiring coming off it is 12 AWG, another instance of insufficient wiring (IMHO).
- Constant power drain, even when the vehicle is turned off – will drain a battery in approx. 1 week if not driven – WTF?
The Infinity system DOES include a vehicle immobilizer feature which is nice, but I’ve purchased a separate Passive Keyless Entry (PKE) alarm system which (to me) is nicer and more sophisticated than what my Infinity system can do. Apparently a fair number of others must agree as there’s a blog written by Infinity which walks through how to incorporate a PKE system with theirs.
So for now I plan to:
- Wire the GMPP control system completely separate of the Infinity system. Reducing the number of systems between the ignition switch and the engine ECM reduces the opportunity for an engine no-start condition.
- Separate HVAC control from Infinity system.
- Use the Infinity system to control vehicle lighting.
It’s a lot of expensive stuff just to control lights! In fairness this is due to me deviating from the intended build configuration – I’m not using the KOSO dash (which is fully integrated via the Infinity system) and I’m not using the immobilizer (because I want the PKE feature). If I hadn’t made these 2 decisions then it might make a lot more sense to integrate the Infinity system as it was intended. I’d strongly recommend builders take a close look at their wiring to ensure it’s adequate, especially for the fuel pumps and fans.
If I’m totally off the mark on my interpretation of the Infinity system’s capabilities and usefulness I’d love to hear from y’all before it’s too late to reverse course from my intended plans!
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