Hi, some time ago, I get DTC code 1860 from my blazer.
in trany shop, they check it, they change pwm solenoid but still code appears.

Today i perfomr the diagnostic procedure descibed in https://blazerforum.com/forum/diagno...plained-28395/, but i had some doubs

1- Step 5: I can do it because I dont have the scan tool. Any Idea?
2- Step 6: I measure voltage trough E and U pins, and the multimeter measures 6 to 7 volts. It can be considered as "lap on" or not?
3- Step 15 i dont inderstand: i need to measure ground to every single pin in C2 vcm connector and 20 inline at connector or only to the line related to PWM solenoid?

Things already done:
- resistance between pin U and E is 11 ohms
- VCM to inline 20 pin connector, for PWM line seams to be ok (1.6 ohms) (C2 vcm conector pin 7 to U connector at AT inline)

Know.. it seams to be necessary to remove valve cover, right?

Best Regards

 

Come on guys!...

 

The 1860 code isn't from a problem with the pwm solenoid, it's telling you the tcc is slipping and that is caused by the tcc regulator valve bore being worn to the point it can't hold oil pressure to keep the tcc fully locked. PWM wasn't one of GM's better ideas, so you will need a different valve body or there is a replacement valve from sonnax that will ream out the bore so you can keep yours. The problem with the PWM system is the regulator valve is always pulsing and wears out the bore so oil leaks by.
If you do get a different valve body, be sure to remove the little short spring in the tcc regulator valve and replace it with a full length one which will change it to an on and off system which is what they used to be and always work. Oh wait this is all for the 1870 code, i'm sorry i was thinking of the wrong one. I would first check all the connections you can and did they clear the code after installing the new solenoid?

 

O man, at the beginnig I start to frighten like hell, since tranny shop did do something in torque converter (they supose to disassemble it, test it, repair it and something else), but it is for code 1870 ufff.

It seam I need to manual ground PWM solenoid, check if it is working and if answer is yes, change harnes and solenoid it self. more money for my gas and money glutter little monster...

A question: It is normal that 4 gear takes long to shift?. I test a Trial Blazer and 4 shift goes almost instantanly at 1500/1600 RPM (driving like granny), but mine takes considerably longer (more than 10 or 20 seconds). I'm considering to buy the Transgo kit along with harness and solenoid (since it could be cheaper to ship all thing along to Chile..

Thanks you for your reply!!

 

No it shouldn't take more than half a second at any speed, it sounds to me like your 2-4 band is gone along with the reverse drum. If you have the pan off you can see enough to tell if that's so. Have you driven it with a scanner hooked up to it so you can see what gear it's in or at least if the pcm is commanding it. And is the oil burnt or nice and red?

 

Wow,oil is nice and red.
Al gear shift quickly but 4 gear. Tranny went to shop 3 months ago for a rebuilt.
Im thinking wiring harness is Gonne, since according to some sobres TdC code 1860 inhibist 4 gear.
Dammit!, I pay a lot for the rebuilt...!!

Since I don't get a scanner capable to shows gear, I calculate the relación between speed, rpm and final velocity. Mine case, at 60 km/h, engine whole be 1290 rpm in 4 gear, but keeps at higher rpm for a los of time.

Tranny shop again, hope warranty works this time.

 

If your oil is ok, then maybe the 3-4 solenoid isn't working right or the valve is a little sticky, or even leakage by the 3-4 accumulator piston. But yeah if you just had it done take it back to them and let them figure it out. Interesting to know what they find.

 

Thanks. The mechanics says that the 4 gear is actuated only by pressure, and bla bla , then it doesn't shift al low rpm as quick as other gear and bla bla. But ok, I will bring him the truck on monday to redone a complete check and demostrated, with a "high tech scanner" how PCM orders tranny. A waste of time, but ok (i just say him "check the wiring please" and he change PWM solenoid...).
Oh, I hope the take truck to shop: today I get a heavy oil leakage, oil sending unit read 0 KPa, and I get oil all over the hood. Engine is running fine (at least). It seams front seal crankshaft seal is gonne (according to the "oil spray" inside hood).... great..., just one more and I will burn her!!!

 

You are just having a time with that thing aren't you. Did you figure out your oil leak? Hard to believe a front seal could give out just like that.

 

Hi!, thanks for your message and sorry for delay, in Chile we had 4 days long weekend, so I preffer to go countryside for a couple of days.

The oil leak was massive and the reason to get 0 pressure was oil pump run out of oil. Before remove air filter, accesory belt I just start to figure out where the leakage cames. Finally, using my CSI skills I found the problem was a lose quickconnector from oil cooler (at main cooling radiator). It just popout and oil get free around my hood.
I didn't found any thing wrong with connector (flexible hose had a small leakage), so since in Chile there is none place to buy the connector, I can just change orings and wait for get part from US, from dealer or something.
Oh, and crankshaft front seal is just fine

So, since I had just more than three problems in just 3 months, I'm starting to think that this truck had more inner troubles. So now annalizing if change truck and try a more new trialblazer unit or something like that (I love 2 door blazer moder, but it seams truck don't love me)... dammit I even get the truck model kit!!!

Tomorrow, tranny shop day.