Hello!

I have a 98 S-10 Blazer with approx. 73500 miles on it that is showing the codes P0740 & P1860 codes intermittently. The engine light does not stay on, but will come on one day and go off the next. It feels to be shifting and downshifting correctly. I have read posts on here that say these codes can come from a faulty ignition switch, but it turns over fine. The only issue with that is that sometimes it will start really abruptly. Could this be the ignition switch, or would it be something else? I have also read that these codes are both related to the TCC curcuit... but it is not coming up with any other codes, just these two. Any help would be greatly appreciated!

Thanks in advance!
April

P.S. I just bought the truck on Nov 11... only 6 days past the AZ implied warranty... any advice there? :-)

 

Diagnostic Sheets:
P0740 - Torque Converter Clutch Circuit
P1860 - TCC PWM Solenoid Circuit

Since these solenoids get their power from the IGN 0 contacts in the ignition switch (see the Anatomy of the Ignition Switch link in my signature), it is possible that the ignition switch could be the source of this problem.

 

The same day the trouble codes started happening the driver's side power window stopped working as well. All of the other windows work fine. Could this be related to the ignition switch too?

Thanks!
April

 

I would say that the window issue is unrelated since it doesn't affect all of the windows. All windows are controlled through the master switch on the driver door so your problem is likely either the driver side window motor or the switch for the driver side window.

 

I had a mechanic recommend to try having the transmission flushed then go from there. I am not sure. I am actually leaning towards the ignition switch being bad or checking the circuit going to the TCC instead. What would you recommend?

Also, the driver side master switch controls all of the other windows fine, so it is probably the motor. Easy fix... more worried about the TCC issues...

 

You could try putting a wire tap onto the IGN 0 wire and monitoring its output while driving down the road.

 

1998 chevy blazer troublecode P1870. What does that mean?

 

Rather than post in a thread which isn't really on the same topic, a quick search would have given you the details you seek.

 

Dear Administrator,
I HAD the same problem, and am HAVING the same problem now. I have Codes P0740 and P1860, as well as P0101, P0102, and P0300. I have Notes on this problem from before, not sure when though. I'm looking over them, trying to remember. But the same thing happened before, with me as well, the Driver's Side Power Window stopped working. It has stopped working now as well. I'm trying to check to see if I had replaced the Ignition Switch, I think I may have. I think, at the same time, I checked and changed a few fuses, then the Driver's Window worked. I checked all fuses this time, and nothing. But I don't even know which fuse is for Driver's Window, nothing says which one is it.
Now, the Battery just "cuts off". Clearly there is power in the battery, but it just goes "dead" when try to start it. It seems to me that it is "cutting off", that there is a Short Circuit, drawing power out of battery. That this "cut off" is related to Driver's window, but not the others. Before it didn't work, then it worked fine for a long while, now it doesn't work again - when these Codes came up. I have never taken off the door panel, to look at window motor or anything. It seems to be an odd "glitch".
But what exactly is the Torque Convertor Clutch? Circuit? As well as P1860 - "TCC PWM Solenoid Circuit Electrical/Transmission Transfer Case Contact Plate "D" Short Circuit to the Battery"? My thinking is that the problem is the Latter - "....contact plate "D" short circuit to the Battery". What is that? Am I think that that is in the Ignition Switch? As soon as I remember what and where the heck that is!!!

Thank you.