Frequently Asked Questions

All late model PCMs including LSx, series PCMs have service numbers on them.  Look for a sticker on the PCM with SERVICE NO. ########.  In most cases the service number is not as important as the calibration on the PCM.  Our 60506 & 60507 LS1 harnesses are built specifically to fit on PCMs with service number 16238212.  The rest of our LS1/LS6 harnesses work with PCMs with service number 12200411 as long as it is flashed for V8 operation and matches your specific engine/transmission setup.  If you have the correct PCM for our harness but want to change the calibration please visit the PCM flash area of this website.  If you have already purchased a Painless harness after April 8th, 2008, we will flash your PCM for free.

1997-2004 Corvettes came with LS1/LS6 engines fitted with throttle by wire throttle bodies and electronics to operate them.  Painless harnesses 60522 & 60523 are direct fit transplant harnesses for these engines/transmissions.  You must have the accelerator pedal and TAC module from a 1997-2004 Corvette to match your PCM programming.

All LS1/LS6 equipped vehicles came with a slue of emission control devices.  Painless offers add-on emission harnesses for those that need the factory emission devises to operate in their transplant vehicle.

Fuel Injection Harness/Emissions Harness

60506/60318

60507/60319

60508/60324

60509/60325

The factory electric cooling fans are controlled by the ECM and are calibrated as such.

• Fan 1 on:  226F
• Fan 1 off:  217F
• Fan 2 on:  235F
• Fan 2 off:  226F

Painless offers a free ECM reflash that includes cooling fan calibration modifications.  Most people change both of the cooling fan operating temperatures to.

• On: 210F
• Off: 195F

Injectors:  Here are a few pointers in order to rule out bad/stuck injectors as the culprit of a no start situation. *Make sure the battery, engine, transmission, body and frame all have large gauge clean ground cables to each other.*

1. If you have noid lights available to use plug them in and see if they pulse when cranking the engine.  If they don't go to step #2.  If they do pulse, check the fuel pressure is close to 58 psi at the fuel rail when cranking the engine.  With 58 psi at the rail and the ECM commanding the injectors to fire, your engine should be recieving fuel.  That is unless the injectors are clogged or stuck.  A good rule of thumb for these type of injectors is if the engine hasn't run for more than 2 months stuck injectors are a possibility.  Either have the injectors cleaned at a performance shop or build a DIY injector cleaning apparatus. 
2. Do the injectors have battery voltage with the ignition key in the run and crank positions?  Unplug all 8 injectors.  Grab a Volt/Ohm meter from your tool box and check to see if there is battery voltage on pin A of the injectors with the ignition key in run and crank.  Ground lead of the VOM connects to the engine.  If battery voltage is measured go to step #3 below.  If you don't have voltage check to make sure the injector fuse in the fuse block is not blown.  Next check that the fuse has battery voltage with the ignition in the run and crank positions.  If you still don't have battery voltage, check to make sure your check engine light stays on with the ignition key in the run and start positions.  If it does not, the MIL fuse in the fuse block is blown or the ignition wire for the Painless harness is not recieving 12 volts it needs to activate the two relays mounted to the side of the fuse block or it is losing the 12 volts during cranking the engine.
3. All LS1/LS6 ECMs have an anti-theft strategy with in their calibration.  This strategy shuts off injector pulse within 2 seconds of engine run if it is not defeated or turned off.  All Corvette ECMs must be reprogrammed to delete there anti-theft strategies.  All Camaro/TransAm ECM anti-theft strategies can be defeated with Painless VATS module 64024 or reprogramming.
4. A faulty or unplugged crank position sensor can also cause the injectors to pulse erratically or not at all.

1. Unplug #1 coil wire from the spark plug.  Plug a known good spark plug into the boot and hold the threads of the plug to the engine block.  Crank the engine and you should see spark.  If no spark is evident go to step #2.  If you see spark then your no start situation is most likely not caused by a coil problem.  Take a look at the injector section above.
2. Does the check engine light stay lit with the ignition switch in the run and crank position?  If it does not, the MIL fuse in the fuse block is blown or the ignition wire for the Painless harness is not recieving 12 volts it needs to activate the two relays mounted to the side of the fuse block or it is losing the 12 volts during cranking the engine.
3. Do the coils have battery voltage with the igntion switch in the run and crank position?  Get out a VOM and unplug one of the inline, white, 7 pin coil connectors.  Check for battery voltage by connecting the black lead to pin A and red lead to pin H of the inline coil connector with the key in the run position.  If battery voltage is present go to step #4.  If no voltage is present switch the VOM to continuity.  Check for continuity from pin A to the engine block or known good ground.  No continuity here means either the ground wire for the Painless fuel injection harness was not connected to the engine, connected to a bad ground on the engine or the engine is not grounded to the battery.  If you have continuity here check for battery voltage on pin H of the inline coil connector this time connecting the black lead of the VOM to the ground post of the battery.  No voltage means you have either a blown fuse in the fuse block or the ignition wire for the Painless harness is not seeing 12 Volts in the run position or you have a faulty ignition relay on the side of the fuse block.
4. Is the crank position sensor plugged into the Painless harness.  This is the sensor located just above the starter on the passenger side of the engine.  Timing is based on this sensor signal.

No you don't; LS1/LS6 ECMs can operate as speed density if you so choose to not use the MAF sensor.  In order to do this the MAF sensor codes must be turned off with software.   With the ECM not actually looking for the MAF sensor it reverts to reading the MAP sensor signal to base engine load calculations from its calibration tables.

This can affect the drivability of your vehicle in a negative way.  Example would be throttle response.  So, if at all possible, we suggest you keep the MAF sensor plugged into your Painless Performance harness.

Most LS1/LS6 engines use a single feed with no return fuel system.  The fuel system must maintain fuel pressure of 55-60 psi.  We recommend using a Walbro 255 fuel pump with a AC Delco GF822 fuel filter.  This fuel filter has a built in fuel pressure regulator designed to work with LS1/LS6 engines and also utilizes quick connect fuel fittings.

The final drive ratio utilized in 1999-2002 Camaro Z-28 and Trans Am cars was 3.23:1. The rear tire on these vehicles had an overall diameter of 25 inches. Transmission shift schedule calibrations are based around this rear end gear ratio and tire diameter. Most likely your rear end gear ratio and tire diameter is different than this. If so, without a calibration change to the transmission shift schedules your vehicle may up shift late/soon and down shift late/soon. You may also experience improper torque converter lock up operation. 

LS1/LS6 engines all came equipped with Delphi EV1 injectors. Different part numbers have different lb/hr rated injectors. 12533952, 12482704, 12561462 are rated 28.6lb/hr @ 58psi. 12456154, 12555894 are rated 26.2lb/hr @ 58psi.