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Haltech elite 2500 w/LS1 Premium terminated harness issues!

Practical Motorsport Wiring - Club Level

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I have a 2002 Firebird ws6 with a fully built RHS ALUMINUM LS 427 in.³ that has the stock GM/Ac Delco 24x 3 wire 12v crank sensor. I am installing my, part #HT-141360 Haltech elite 2500 w/ gen3 Ls1 Premium terminated harness and having issues with voltage on the wrong pins with crank sensor plugged into harness. I have deleted/removed the Haltech relay/fuse box from my harness and re-wired a custom relay board with overhead switch box from Jolt Systems. It was a fairly straightforward removal and re-pin of the switched 12V wire “pink” to “Ignition on”button. When I push the button for ignition “on” I am getting 12V on pin A9 “5v sensor supply power” and also 12v on B14/15/16 “signal ground” with crank sensor connected. I disconnect the crank sensor from harness and get 0V on Pin A9& B14/15/16. Definitely has thrown me for a loop. Any help would be greatly appreciated. This is a brand new Haltech harness. I have no other sensors connected. I do have 12V on pin A13,A25 and A26 along with B11 like I am supposed to. I HAVE NOT CONNECTED ECU TO HARNESS. And do not plan to until I get this issue resolved. I am checking voltage and continuity with a fluke multi meter. I have a Main dedicated 2 AWG power wire Straight from battery to a power pass-through at firewall. I have another 2AWG power wire running from battery Straight to starter. I am using a 0/1 gauge from battery to Chassis for ground. Then I have a 2awg ground wire straight from battery to firewall pass thru that is grounded to the bottom trans bolt to block. Also have a ground strap from front of block to frame rail. Been trying to figure this out for three days now. I have the ECU ground straight to battery as well. Thank you looking for feedback and how to resolve this issue so I can plug connectors to my elite 2500 so we can update firmware and fire the motor back up. Cheers


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No one? Really trying to sort this issue out asap. Any help would be greatly appreciated, thanks

I think you are making a mistake not connecting the ECU to the harness. It is what supplies the 12V, without it connected who knows how signals will float.


I am afraid that I am going to smoke/burn up my elite 2500 if I plug the connectors A&B to it with having my Multi meter reading 15.32v on “all” my “sensor ground”pin B14/15/16. I have checked continuity and everything is zero. By plugging the elite up to the connectors what processing will that do for sensor grounds that are already reading super high voltage. I am running a 16 V lithium battery. Thanks for your help

If your harness is connected to 12V, but the sensor grounds are not connected to the ECU, they will be essentially "pulled up" by the resistance in the sensors. You need the ECU to be connected in order for the ground pins to have 0V.

One way to verify this, connect the ECU to the harness, but not the battery. Now measure the resistance between the Harness Battery 12V and Harness Battery ground. This will verify there is no short. Measure the resistance between the Sensor Ground and the Chassis Ground. This should be close to zero volts.

Seriously, the harness circuits 0V are connected through the ECU -- not having that will lead you to all sorts of seemingly bad voltage values.

Another safe way to approach this -- Remove all sensors, connect only the ECU, Battery 12V and Ground Disconnect all other sensors, solenoids, relays, coils, injectors. You can then verify the signals at each connector as you connect the other parts back up.

Thanks for your help, that does make sense. I have been chasing this for 3/4 days now. Your explanation definitely helps me feel more confident with connecting elite 2500 ECU to A&B harness connectors. Just to clarify, I have removed the Haltech relay/fuse box and installed a custom relay board with overhead switch panel set up for my car, so my harness has power when main/ignition “on”button is activated on switch panel. It’s wired with 12/16v from pin A13 along with 12/16v switched ecu supply power at pin B11 as well. I will let you know how everything goes, but will try to test the resistance between the ecu power and ground first. Again I appreciate your help and feedback. Just really threw me for a loop when I connected my GM/AC Delco 24X 3 wire 12v Crank sensor to connector on harness and started seeing 15.32v across all sensor grounds B14/15&16 and A9 5v sensor supply. That has had me super worried. Much appreciated. Will report back after I test and connect ECU. Thank you very much for the explanation.

Thanks again, David.

so far so good, with all voltage and 5v are all sitting at 4.80/4.95 the only one a bit higher is oil pressure @5.76 but need To be calibrated because it’s also telling me in the software that it’s at 1.30psi. Each signal ground I have checked is .015 with connectors plugged in to ECU. Haltech support still thinks I have issues somewhere but plan to talk via phone with em tomorrow. Just wanted to update you. Your help is much appreciated, Sir. Now of we can get the ecu over to NSP we will get a base map to fire it back up but, now boosted of course ;)

Happy to help, and glad to hear you are making progress.

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