No throttle, p1518
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Joined: Sep 2013
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From: Cape Coral, Florida
All power and grounds get loaded circuit voltage drop checked…watch the video !!…best to study basic electricity…you can find some great training on YouTube.
Last edited by C5 Diag; Sep 19, 2025 at 08:03 PM.
Thread Starter
Heel & Toe
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New codes
So I watched the videos, makes sense, all seemed to be good but then I found about 40 ohms of resistance from the tac ground pin to ground, earlier tests I thought were 0.5. So I cut the wire a few inches up and ran a new ground to the battery, now the pin has 0.1 ohms of resistance. I also found that my battery negative to ground is about 40ohms, so I pulled the battery negative strap and cleaned the terminals that goes to the block, starter, battery negative, and the small ground over the battery.
Cleaned the actual grounds and put all back together. started the car and no p1518… but p1220 and p1221.
I tested the tps with a dmm yesterday and it works as far as I can tell. Sweep seems to be smooth when you manually move the throttle.
Cleaned the actual grounds and put all back together. started the car and no p1518… but p1220 and p1221.
I tested the tps with a dmm yesterday and it works as far as I can tell. Sweep seems to be smooth when you manually move the throttle.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
So I guess you are still using resistance measurements instead of voltage drop…you should be testing the TPS wiring…1220 is TPS 2 voltage is greater than 4.87 or less than 0.13 volts and 1221 is a 7.5% difference between TPS 1 and 2…I prefer a labscope over a DMM in that I can take millions of voltage samples every second vs a DMM which has a very low refresh rate…TPS sensors are basically 2 simple potentiometers.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,490
Likes: 3,999
From: Cape Coral, Florida
Do you know how to check these TPS sensors ??
Last edited by C5 Diag; Sep 23, 2025 at 05:31 PM.
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Thread Starter
Heel & Toe
Joined: May 2025
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Results
Yellow and black - 5v constant with ign on
pink- 3.8v at rest, 4.48v held close, 1.8v open
dk blue- 4.75v open, 1.2v rest, .51v held closed.
dk green- 4.99v constant
both low ref to battery ground are 26 ohms
pink- 3.8v at rest, 4.48v held close, 1.8v open
dk blue- 4.75v open, 1.2v rest, .51v held closed.
dk green- 4.99v constant
both low ref to battery ground are 26 ohms
Last edited by 1997 issues; Sep 23, 2025 at 05:49 PM.