TCC Slippage - Good Find I値l Share
Thread Starter
Teching In
Joined: Jul 2024
Posts: 35
Likes: 11
From: Redcliff, Alberta, Canada
TCC Slippage - Good Find I値l Share Hey guys,
I had a great find today that I am honestly shocked I caught on my scan tool as normally an issue like this I壇 have to be hooked up with my oscilloscope to catch.
97 GMC 1500 / 4L60E
Customer Concern: Slipping Out of Lock Up at Times
Before my test drive I had already dug out a spare TransGo On/Off TCC valve ha ha ha as I figured I had a pretty good idea of what I was in for, but my diagnosis went a different direction!!
Took truck for test drive, was able to verify the complaint however very inconsistent and short/fast slips in and out of lock up. No codes stored anywhere, which was a little odd to me and had me questioning a genuine TCC valve issue. Had some trans data logging of course at the time, and I noticed sometimes TCC enable would flicker and sometimes not when the concern happened. OK strange I thought. I decided hmm I should look at some ECM data, Brake Switch, TPS, ECT, MAP, etc just to be thorough. After a 30 minute drive and after narrowing down my data stream to just ECT and Open/Closed Loop PIDs, I noticed very randomly and very quickly the ECT would go from the usual 195F to wildly low numbers and back up. I actually didn稚 catch it on the graph, I caught it on my min/max. When I rescaled my graph on my Loop Status, I then started to notice tiny flickers in the loop status that coincided with the TCC slip. Got back to the shop, hooked up the meter to the ECT and low and behold it had a tiny tiny crack in the sensor body that would cause an open circuit when wiggled a certain way. New ECT sensor, $17 part, a post repair drive and data log to confirm the repair and I had one happy customer on my hands - issue resolved.
Thought I would share this drivability diagnostic with ya値l to keep in mind as it had me laughing at the end of the day after dealing with a morning of nightmares!!
Cheers!
I had a great find today that I am honestly shocked I caught on my scan tool as normally an issue like this I壇 have to be hooked up with my oscilloscope to catch.
97 GMC 1500 / 4L60E
Customer Concern: Slipping Out of Lock Up at Times
Before my test drive I had already dug out a spare TransGo On/Off TCC valve ha ha ha as I figured I had a pretty good idea of what I was in for, but my diagnosis went a different direction!!
Took truck for test drive, was able to verify the complaint however very inconsistent and short/fast slips in and out of lock up. No codes stored anywhere, which was a little odd to me and had me questioning a genuine TCC valve issue. Had some trans data logging of course at the time, and I noticed sometimes TCC enable would flicker and sometimes not when the concern happened. OK strange I thought. I decided hmm I should look at some ECM data, Brake Switch, TPS, ECT, MAP, etc just to be thorough. After a 30 minute drive and after narrowing down my data stream to just ECT and Open/Closed Loop PIDs, I noticed very randomly and very quickly the ECT would go from the usual 195F to wildly low numbers and back up. I actually didn稚 catch it on the graph, I caught it on my min/max. When I rescaled my graph on my Loop Status, I then started to notice tiny flickers in the loop status that coincided with the TCC slip. Got back to the shop, hooked up the meter to the ECT and low and behold it had a tiny tiny crack in the sensor body that would cause an open circuit when wiggled a certain way. New ECT sensor, $17 part, a post repair drive and data log to confirm the repair and I had one happy customer on my hands - issue resolved.
Thought I would share this drivability diagnostic with ya値l to keep in mind as it had me laughing at the end of the day after dealing with a morning of nightmares!!
Cheers!
Hey guys,
I had a great find today that I am honestly shocked I caught on my scan tool as normally an issue like this I壇 have to be hooked up with my oscilloscope to catch.
97 GMC 1500 / 4L60E
Customer Concern: Slipping Out of Lock Up at Times
Before my test drive I had already dug out a spare TransGo On/Off TCC valve ha ha ha as I figured I had a pretty good idea of what I was in for, but my diagnosis went a different direction!!
Took truck for test drive, was able to verify the complaint however very inconsistent and short/fast slips in and out of lock up. No codes stored anywhere, which was a little odd to me and had me questioning a genuine TCC valve issue. Had some trans data logging of course at the time, and I noticed sometimes TCC enable would flicker and sometimes not when the concern happened. OK strange I thought. I decided hmm I should look at some ECM data, Brake Switch, TPS, ECT, MAP, etc just to be thorough. After a 30 minute drive and after narrowing down my data stream to just ECT and Open/Closed Loop PIDs, I noticed very randomly and very quickly the ECT would go from the usual 195F to wildly low numbers and back up. I actually didn稚 catch it on the graph, I caught it on my min/max. When I rescaled my graph on my Loop Status, I then started to notice tiny flickers in the loop status that coincided with the TCC slip. Got back to the shop, hooked up the meter to the ECT and low and behold it had a tiny tiny crack in the sensor body that would cause an open circuit when wiggled a certain way. New ECT sensor, $17 part, a post repair drive and data log to confirm the repair and I had one happy customer on my hands - issue resolved.
Thought I would share this drivability diagnostic with ya値l to keep in mind as it had me laughing at the end of the day after dealing with a morning of nightmares!!
Cheers!
I had a great find today that I am honestly shocked I caught on my scan tool as normally an issue like this I壇 have to be hooked up with my oscilloscope to catch.
97 GMC 1500 / 4L60E
Customer Concern: Slipping Out of Lock Up at Times
Before my test drive I had already dug out a spare TransGo On/Off TCC valve ha ha ha as I figured I had a pretty good idea of what I was in for, but my diagnosis went a different direction!!
Took truck for test drive, was able to verify the complaint however very inconsistent and short/fast slips in and out of lock up. No codes stored anywhere, which was a little odd to me and had me questioning a genuine TCC valve issue. Had some trans data logging of course at the time, and I noticed sometimes TCC enable would flicker and sometimes not when the concern happened. OK strange I thought. I decided hmm I should look at some ECM data, Brake Switch, TPS, ECT, MAP, etc just to be thorough. After a 30 minute drive and after narrowing down my data stream to just ECT and Open/Closed Loop PIDs, I noticed very randomly and very quickly the ECT would go from the usual 195F to wildly low numbers and back up. I actually didn稚 catch it on the graph, I caught it on my min/max. When I rescaled my graph on my Loop Status, I then started to notice tiny flickers in the loop status that coincided with the TCC slip. Got back to the shop, hooked up the meter to the ECT and low and behold it had a tiny tiny crack in the sensor body that would cause an open circuit when wiggled a certain way. New ECT sensor, $17 part, a post repair drive and data log to confirm the repair and I had one happy customer on my hands - issue resolved.
Thought I would share this drivability diagnostic with ya値l to keep in mind as it had me laughing at the end of the day after dealing with a morning of nightmares!!
Cheers!
We can already see what is happeneing to these later model vehicles that are completley controlled by this stuff...throw them away
Thread Starter
Teching In
Joined: Jul 2024
Posts: 35
Likes: 11
From: Redcliff, Alberta, Canada
Great info, Ive noticed more and more "Issues" like this as the vehicles I work on are getting older and older.... these sensors, computers, and wiring problems are becomeing more and more prevalant.
We can already see what is happeneing to these later model vehicles that are completley controlled by this stuff...throw them away
We can already see what is happeneing to these later model vehicles that are completley controlled by this stuff...throw them away
