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Polaris side by side ECU and harness upgrade

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This is my 2011 Polaris Ranger 800. This has been an awesome machine and has taken me places off-road I probably never should have been! Unfortunatly it has had some issues since new and only gotten worse over time.


1.) TPS wiring: This 800cc engine is not a smooth running engine. Due to the vibrations particular parts of the wiring harness have been known to suffer from broken wires. Polaris tried zip-tieing the wires in all sorts of ways but given the design and build of the harness it's a futile attempt.

2.) No known way to trouble shoot or tune the EFI system. This is made obvious once you start having issues with the TPS and inconsistent idle rpm's. You are left probing the sensor and physically adjusting the throttle blade to get the voltage with-in specification rather than setting the throttle where it belongs and adjusting the parameters.

3.) I feel the manufacturer has left a lot of performance on the table. This particular year engine has a rather robust array of sensor that could be leveraged to pull the most from the engine.

Project goal:

1.) Remove and replace the factory ecu with a aftermarket unit that will allow me complete control.

2.) Design and build a new wiring harness that corrects the factory shortcomings.

3.) Design or procure a higher quality throttle body.

This machine is going to be my testbed for my future business. I have been a CAD operator / Detailer since 1998 with a Machinist background. I recently suffered an "Eye stroke" in my left eye causing me to lose vision in that eye. Now days I have to take a lot of breaks from the monitors as my one good eye gets strained and negatively affects my productivity. Therefore I am going to attempt to start my own small business, designing and producing parts for the off-road community. I already own this machine and know all of it's downfalls.

I joined HP Academy many moons ago with the intention to learn engine management tuning for my race vehicles.

I guess I will start with what sensors are present in stock configuration.

TPS / T-map / TPS / Cam phase sensor / speed sensor / IAC / EPS (electric power steering)

fuel pump / stator / regulator

parking brake / brake line pressure / front differential lock / rear differential lock

I have not thought about the EPS and which aftermarket ECU offer EPS management. The factory ECU uses the speed sensor to regulate the power steering assist. It's a common issue to damage the speed sensor and the steering light come on.

At minimum with this project I want to build a new harness using quality wire and better harness routing.

I want to share more pictures but having difficulties.

Sorry folks, My body is falling apart and been busy with doctors and hospital! I want to try to reflash the factory Polaris ECU. I am on the hunt for the hardware and software that will allow me to do this. I also want to try my new found wiring harness skills out by building a replacement factory harness except with higher grade materials and the professional techniques shown in the classes.

I contacted a small business that makes patch pigtails for this model which work for almost all situations. Link to the company bellow, as you can tell Polaris suffers from harness issues. So much so a company is making a living off of the issues. I have asked them if they could sell me all the connectors and pin's but I'm doubtful they will.


I am also working on heat shielding. I will try to add a photo but I have had a lot of issues uploading images to this forum from my location.

Since this picture was taken I have added some heat protection to the fuel line and some reflective heat material to the fuel tank. The exhaust is aftermarket, it came wrapped but water deteriorated the wrap to the point it started falling off. Heat use not be an issue as I mainly rode in mud and deep water. As you can tell I took the big lift off and plan to stick to trails now.

I will be making new heat shielding as the passenger side gets extremely hot after 30min of riding.

Attached below is a picture of the old suspension setup and the current setup. The big suspension lift put a lot of stress on the CV joints causing a lot of heat. I wasn't able to run the machine very fast or long out of water. It would melt the CV boots and actually had the grease and boots catch fire. I would routinely have the bed submerged under water at the local mud parks.

The machine only has 1,300 miles but I have been thru 4 transmission, 3 front differentials, countless wheel bearings, suspension bushings and 3 steering racks. I can no longer afford to keep the machine as a mud machine, thus the removal of the crazy suspension. I hope to trade the wheels and tires for something less aggressive in a 28" diameter tire.


As you might be able to tell, I have got off this project and focused on my Ford truck project. I got this Polaris Ranger SXS running good enough to call it "running". Unfortunately it has developed more wiring issues.

The T-MAP sensor has developed exposed copper and causing all sorts of running issues.

As I mentioned earlier in this project thread. This model UTV suffers from poor wiring from the factory. The engine shakes, extremely hot and stuffy engine compartment. I really want to build my own harness using the lessons learned from this website but I don't want two projects going at the same time.

I have already replaced the pigtail to the TPS.

Throttle body

Heat is the biggest issue and I have been meaning to create a final solution but haven't. The exhaust was wrapped but it doesn't last long being constantly submerged in water. It just falls off in pieces.

Coil packs & Factory ECU

For the amount of water and mud all these parts have been submerged in I really can't complain.

Since your images are hosted in a private storage area on the internet they dont appear to anyone else but you mate.

Can you see some pictures now, I can see the pictures even when I'm logged out? (I have never had this many issues with sharing images.)

Yes, they are fine now mate.

Oh the horrors it shows! Easy to see why they have so many issues.

Sorry, I got hit by the covid-19. I ran a 102.9 fever for 9 days then got pneumonia. Today is the first day I have felt like getting on the computer again! Ya'll be careful, there is no rime or reason why it hardly effects some yet stomps others like myself into the ground.

Thats no good at all mate, look after yourself in these uncertain times!

Joshua, hello from a fellow Mississippian, though currently residing a state over in Cajun country. Looks like an interesting project and falls in line with what led me to this site. Sorry to hear you got the 'Rona but glad you are doing better. What part of MS are you from?

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