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90-92 TPI Speed Density Custom Harness
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If you are looking to install a Speed Density TPI setup on your vehicle, you have probably seen a wide variety of wiring harnesses on the market. You have probably wondered what exactly you need, or perhaps needed someone to help guide you figure out what your needs are exactly. As enthusiasts, we have worked with many of these ourselves. We have found that important details are often overlooked, and installation instructions aren't always clear or easy to follow. The average installer has enough on their minds without having to worry about whether or not their harness meets their needs, or if they understood the installation instructions correctly.

We have taken the time to sort out the little details to make sure that your conversion goes smoothly. You will receive a very thorough, and easy to follow installation manual with every harness. All harness connectors are clearly labeled, and each connector can fit only in the correct place. This is a stand alone wiring harness, and has connections for all the necessary ECM related functions. Installation is simple, there are only 4 wires which you will need to run. Everything else will fall into place. This harness is designed to work with the 1227730 ECM.

We build each harness in house, using TXL grade automotive wire, and new GM connectors, terminals, and seals. These are the same components used by GM on factory harnesses. In addition, all our harnesses are GM color-coded. You can use a factory wiring diagram to follow the harness if you any work needs to be performed on the vehicle. Each harness is thoroughly tested before shipping out to ensure a trouble-free conversion.

Each harness comes standard to work with the components specified below unless you specify otherwise.

  • Manifold Absolute Pressure Sensor (MAP)
  • Throttle Position Sensor (TPS)
  • Idle Air Control Valve (IAC)
  • Coolant Temperature Sensor (CTS)
  • Manifold Air Temperature Sensor (MAT)
  • Knock Sensor
  • Oil Pressure Switch
  • Oxygen Sensor
  • Distributor
  • Injectors
  • EGR solenoid
  • 700R4 Torque Converter Lockup (TCC)
  • ALDL Diagnostic Connector
  • Check Engine Light
  • Vehicle Anti-Theft System (VATS)
  • Park / Neutral Indicator
  • Fuel Pump
  • Fuel Pump Relay
  • Electric Cooling Fan Relay
  • Cruise Control
  • Air Conditioning
  • Vehicle Speed Sensor (can be setup for a 4000 or a 2000 pulse sensor)

Our standard harnesses (as described above) will have 54 inches between the ECM connectors and the distributor connector. It is setup for a small cap distributor, old-style relays, and for the old-style oil pressure switch which mounts by the distributor.  Chances are however, that you have specific needs and a standard harness may not be the best choice for you. In this case, we can build a harness specifically tailored to your needs. Each harness is built once ordered. Turnaround time is about 1 week.  However, we may take longer if there are other harnesses waiting before your order, so contact us first if you are in a hurry. If there are connectors or wiring that you will not be using on your application, you can let us know in the comments box, and we will not include them in your harness.

Tech / Support
Our installation manual is very easy to follow, and very complete. If you run into any questions however, we are available at your request via email or phone to answer any questions you may have.

You can pick and choose from the options below to specify what you need for a custom harness. If you have any questions or would like to discuss other options, feel free to contact us at

Harness Type
Relay Style
Oil Pressure Switch
Harness Length
Harness Length (ECM to Distributor)
Add-On Harness Options
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70 Bama Lane
Clanton, AL 35045

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