No throttle response on first start up
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No throttle response on first start up Hey guys finally started up my ls swap. Was a great feeling to hear her run. But like with any engine start up there are some problems. She is throwing code u0107 meaning the ECU isn’t registering the TAC module. I started by checking all the 5v power wires and low references (grounds). They were all in good shape and show up good with my multimeter. So I thought maybe the sensor in the throttle was bad. Unhooked it and tested it in my other truck. Worked perfectly fine. I then did some research and discovered this was possibly due to a ground problem. So I added another ground strap to the back of the motor to the firewall. Started her up and throttle started working. Great I thought, problem solved but no. Deleted code, turned motor off, started her again for good measure and problem was back immediately. Any idea what it could be? Tomorrow I’m just gonna start by adding more grounds and see if that could be a problem. Would grounding the low reference wires be a problem? Because if that’s an option I’ll just ground them directly to the back of the engine block in the same location I have grounds running to the firewall and frame.
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So I figured out that if I disconnect the battery and start the engine again the throttle starts working but engine runs rough. The battery did die between adding the extra ground strap so I believe the ground strap didn’t help at all. I let it run for a couple minutes and more codes popped up along with it. Mass air flow circuit low, multiple misfire, and codes for evap sensors. I do have the evap system hooked up for emissions in California. It’s looking to me like there is something going on within the 5v circuit. I don’t believe it’s grounds but it could possibly be wrong. My battery is grounded to the block, frame, and body. The heads are both grounded to the firewall. Are there anymore grounds that I am missing?
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Where would they be located, I cleaned up one at the very back of the engine behind the intake but I don’t know of any others. The engine came with the harness attached and I wired the fuse block, evap sensors and gauges myself. I have not seen any grounds to the block removed but maybe I’m missing them. I do receive 5v through the 5v reference wires when I ground them through the low reference. Could I be getting some kind of interference through the grounds?
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Thread Starter
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Anyone got ideas? I removed the TAC module from my other truck and plugged it into the LS swap and it didn’t solve the problem. So I know the foot pedals not bad, TAC modules not bad everything is receiving 5v reference like it should, and I have ground through the low references. Everything should be working right? Only thing I can think of is ground noise or a bad ecm. How can I check if I’m getting ground noise? I’ve done research and have read that this 5v circuit is very finicky when it comes to ground locations.
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Originally Posted by 86K5lq9
Hey guys finally started up my ls swap. Was a great feeling to hear her run. But like with any engine start up there are some problems. She is throwing code u0107 meaning the ECU isn’t registering the TAC module. I started by checking all the 5v power wires and low references (grounds). They were all in good shape and show up good with my multimeter. So I thought maybe the sensor in the throttle was bad. Unhooked it and tested it in my other truck. Worked perfectly fine. I then did some research and discovered this was possibly due to a ground problem. So I added another ground strap to the back of the motor to the firewall. Started her up and throttle started working. Great I thought, problem solved but no. Deleted code, turned motor off, started her again for good measure and problem was back immediately. Any idea what it could be? Tomorrow I’m just gonna start by adding more grounds and see if that could be a problem. Would grounding the low reference wires be a problem? Because if that’s an option I’ll just ground them directly to the back of the engine block in the same location I have grounds running to the firewall and frame.
With your tac issues, it makes me wonder if a portion of the harness got pinched during motor installation.
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Teching In
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To answer one of your original questions, no I would not ground all the low reference wires. On a factory harness there should be a ground on the back of each cylinder head. This will typically affect coils and injectors when not properly connected.
With your tac issues, it makes me wonder if a portion of the harness got pinched during motor installation.
With your tac issues, it makes me wonder if a portion of the harness got pinched during motor installation.
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I have checked and cleaned all grounds on the block, added news grounds, block to frame, block to firewall, fuse block to frame, and both heads grounded to firewall. Looked over the harness and can’t find any exposed wire. I did notice one of my class 2 serial data wires is not connected to anything (yellow wire) the other wire (also yellow) runs to my obd2 .Is there any use to this second class 2 serial data wire? Also could my tps cause these codes? It is the only thing I have not tested. Both the tach module and foot pedal I tested in my 03 GMC Sierra.