Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
So symptoms of this car is it has no power and can’t be driven basically. Throttle response is minimal. So scan tool data shows tps b1 is fixed at 5.12 volts and tps b2 shows .01 volts. Fault code for b1 voltage high. When I reach down and disconnect the sensor tps b2 returns to 5v and b1 still fixed at 5. So just going across the six pins unplugged I find one 5v feed and another lead with 2.5v which I assume to be a signal maybe. So I continue down the line and don’t find much else maybe grounds low voltage mostly idk atp? So I go looking down the line unplugged at tps while watching data excluding the 5v pin with my ohm meter touch one pin and the data pid b1 circ jumps down away from five I let off it goes to five again. Same for b2 circuit at this point when I touch its signal pin. Now at this point I’m thinking maybe I’ve got a grounding problem since I’ve found the 5v feed is good and signal integrity to ecm seems okay for both circuits signals. So I start checking and I don’t find a ground so I figure why not ground the black wire with a test light it has no voltage on it and no ohms to ground and that’s when my voltage for b1 circuit returned to steadyish .76 of a volt and b2 came off .01 and went to near a volt like b1. Then I unplug the connector and both voltages rise to 5 like I wanted. So at this point i Get in start the car and have great throttle response. I can actually drive the car now. Clear the dtc and it stays off great. Only issue now is it has a code for ISC cause the idle speed is all over the place but I still have good throttle control. So why when I disconnect my ground wire to the tps that my idle speed returns to normal???? Tried all the resets let the customer have it since the vehicle is drivable and the initial complaint of no throttle control is fixed. I Can’t help feeling like I missed something or messed up here. Thanks
The TPS is also the throttle control actuator. So when you unplug it the throttle will go to a fixed position. Whenever you unplug it the vehicle requires closed throttle position and idle relearns.
Haha I need you around more often. I tried some of the above relearns but I suppose they didn’t take. But do you agree on the addition of a ground to the black wire at the tps? So each time i unhooked what fixed it it required new relearns carried out. Is there an order of relearns or does it matter. Done without consult...
Black wire is sensor ground thru' the ECM. I would've dug a little deeper before bypassing it to ground but it should be a fix.
Pretty sure TPS relearn should be done before idle. There's also an APP relearn you could do before those if you're unsure of the history. That one is foot off the gas then key on 2+ seconds, key off 10+ seconds, key on 2+ seconds, key off 10+ seconds. I'd also give the throttle body a quick cleaning before starting the relearns personally.
Thank you Matt. The story I got from the customer was he had autozone swap the battery then drove it for a day then it messed up and wouldn’t drive. The vehicle only has 37,000 miles. Wondered if the ecm grounded that pin or not since the dealer wouldn’t let me know what pin went where. But figured it had to be ground and that it probably came from the ecm but grounding it which made it operational again but like you said I should’ve dug deeper and found why that ground wasn’t there. I should’ve taken the time to make sure each and every variable was met before doing relearns. I did the idle volume relearn since the idle speed was all over the place. But didn’t know if there was a specific order to preform them in. Again thank you for your time.
