4l60e tcc pwm solenoid??

[Tanner]

this has been kind of an issue for a while. in fact I posted on here about it before and I got a lot of good info. however, after that the problem never occured again untill now.

last summer I took my 1996 chevy k1500 to a transmission shop because it had gotten stuck in park. when the shop inspected it they found that a bushing inside the transmission was worn out so the shifter arm was butted up against a wall so it would not alow it to shift out of park. they tried to fix the bushing without pulling the tranny out but reported that the tranny would have to come out. since the tranny was coming out it was MY suggestion just to do a rebuild on it any way because it had 230,000 miles on the original tranny.

the only issue that I had had before then was on my way to work one morning my truck shifted very hard from 1st to 2nd and I got a P1860 code. I cleared the code and never got it again untill about 3 months before It had a rebuild. the truck shifted fine and drove fine but about once a month I would get the p1860 code. the shop found a few worn out parts and found that I was going to lose reverse gear very very soon. the shop showed me all the worn out pieces and explained to me what they did and how they work. ( I have limited knowledge on automatic transmissions.) shortly after the rebuild a hard shift developed and is not a constant issue with the p1860.

I talked to the shop that did the rebuild and he checked it with a scanner and said that if the code is cleared it comes right back without the truck even being put in gear. and that he believed it to be the ignition switch which has a power wire that feeds the tcc pwm solenoid 1-2 solenoid, and I believe the 3-4 solenoid. I checked that I have power on pin E that feeds the shift solenoids.

I am going to school for auto collision repair, the school also has a auto mechanics so I went and talked to their instructor they reassured me that it was probably the ignition switch so I contacted the transmission shop and they said the same thing that it was probably the ignittion switch too. So ignoring my tests and what I found out I replaced the ignition switch and of course it didnt fix it.

once again I talked to the mechanics teacher and they printed out a diagnoses paper for me with a list of possible fixes. ignition switch fixed 96 percent of the p1860 issues. a couple other possibilities is a bad pcm, and a bad tcc pwm solenoid. the transmission shop said that if I diagnose it and find that it is the solenoid that they will replace it under warranty however if they replace it and it doesnt fix it then they would charge me for it. Or they can charge me starting at $100 to diagnose it regardless of what it is.

so since I am just doing the paperwork to graduate from school my instructor is letting me check it out in the shop. everything has tested out good untill I got to testing pin s which is the tcc pwm solenoid. the instructions say to un plug the red plug at the pcm and to have the key to the run position with the motor not running. the solenoid should have a 1 amp draw. the problem is the shops multi meter will only read .2 amp draw and I am not sure if that was direct or alternating current. so this weekend I got a multimeter that will read up to 20 amps direct current and plan on finishing the test tomorrow.

I guess in the end I am wondering if you guys have any more thoughts on what to check or ways to confirm the cause of the issue. the solenoid looks fairly easy to change out however I do not want to void my warranty especially if they will replace it for free if thats the issue. I am also considering just paying he $100 to have them diagnose it if I cant get a solid answer.

I feel kind of like the shop should diagnose it for free considering they rebuilt it. and then depending on what the issue is if its related to something they did or if its just something not related to what they did to charge me for checking it out but they want to charge me regardless.

also just out of curiosity does anyone know if driving it around would hurt the transmission with the solenoids acting up? the tranny shop said as long as i was driving it less than 35 mph it shouldnt hurt it, I am just curious what others think. I am a tow truck driver so its not a huge deal to tow it to the shop if I need to. right now I am driving the tow truck around which my boss prefers anyway but where I AM the tow driver 24/7 I would never get to drive my truck so I usually just leave the tow truck at the shop since I live 4 minutes away.

thanks guys

Topic

[college man]

Kinda what you did see if it helps.

http://www.justanswer.com/chevy/1e57c-fix-code-dtc-p1860-p1886.html

[Tanner]

I actually came across that article earlier it helped me some. This morning I used my new multimeter (ya I’m actually kind of excited about it) to test the solenoid resistance and amps on the plug of the transmission

As per my diagnosis paper I should have roughly 1 amp draw on the brown wire with the key on, red pcm plug disconnected. I couldn’t get any amp reading off it. So I checked voltage just for fun and I have .2 of a volt. The paper also says it should have roughly 15-20 ohms resistance from the power wire that feeds the solenoids to the brown wire with the key on. It would only read 1 or infinity.

So I think it’s safe to say it’s the solenoid. Unless someone has something to add to it? I just don’t want to say replace the solenoid and end up shooting myself in the foot.

[college man]

[quote=”Passey” post=182807]I actually came across that article earlier it helped me some. This morning I used my new multimeter (ya I’m actually kind of excited about it) to test the solenoid resistance and amps on the plug of the transmission

As per my diagnosis paper I should have roughly 1 amp draw on the brown wire with the key on, red pcm plug disconnected. I couldn’t get any amp reading off it. So I checked voltage just for fun and I have .2 of a volt. The paper also says it should have roughly 15-20 ohms resistance from the power wire that feeds the solenoids to the brown wire with the key on. It would only read 1 or infinity.

So I think it’s safe to say it’s the solenoid. Unless someone has something to add to it? I just don’t want to say replace the solenoid and end up shooting myself in the foot.[/quote]

The only thing I can add is on the ohm test unplug the coil and test ohms on the coil by itself.
You can’t read ohms with power to it or on. 😉

[Tanner]

so in case anyone is wondering the problem has been solved. after doing my own diagnosis I had decided that the solenoid had went bad, but since I didnt want to be wrong I let the shop do there diagnosing as well. the technician had it for a week ( i dont know how much he actually worked on it in that time period) they told me that he even came in on saturday and sunday to try and figure it all out.

all said and done it turns out it was the wiring harness inside the transmission that powers the solenoids and all that good stuff. so In a way my diagnosis was half right in that the tcc pwm solenoid circuit was not in spec and not working correct, however it was not the solenoid that was the problem. the shop put a new harness in under warranty and didnt charge me a dime. the truck now shifts really smooth and drives a lot better so it all worked out well in the end. thanks for your help and contribution I really appreciate it!

[college man]

Glad it worked out.

[Author]

Replies