Hey all, first post here, been lurking for quite some time, never really had a reason to post until now. I have an 01 Blazer 4x4 stock as stock can be, and a 2000 S10 bagged, shaved, tubbed, supercharged and wire tucked.

My problem is with the s10. Ive been racking my brain on this one for quite some time (2 months) and have made no progress. Long Story short, I purchased this truck from a friend, Friend paid a "mechanic" to do a very shoddy wire tuck resulting in some pins being pulled from the PCM. With the help of all data, my multimeter, and loads of beer I have pieced everything back together aside from this.

I get the following codes: P0740, P0753, P0758, P0785, P1860

Fuse 11 verified good

Gauge cluster wouldn't power up and after doing some tracing, verified the ignition circuit dead. I ran a new lead from the Ignition switch to the cluster and this got the cluster to power up but the shift indicator is stuck in 3rd and the truck stays in 3rd. The speedometer is also not working.

I pulled the plug on the pass side of the transmission and continuity checked
the following leads at the PCM and connector. Pink, Tan/Black, Light Green, Brown, Yellow/Black, White. That covers the torque converter and shift solenoid wiring.

I have 2 pink wires on the transmission plug, one shows 12v with the key in the run position, and the other does nothing, no continuity, no 12v, nothing. Not sure what it is for. I have yet to see a diagram that shows as many pins as my connector, or has labeled every pin. If someone had a diagram of the trans connector with all pins that would be super.

I'm suspecting the PCM to be defective but am hesitant to try a new one as I have yet to cover all wiring aspects.

Any help from here would be fantastic.

Thank you

 

Did you use the search window?
Ya might find this thread helpful
https://blazerforum.com/forum/engine...5-p1860-61980/

 

I have checked pin E several times, it does in fact read 12V with the key in RUN. I even ran a loose lead from the ignition switch to this wire in the event and still stuck in limp mode. Looking at that pin out I have checked what I should be testing in this situation. I have replaced both shift solenoids and the TCC solenoid. While in there with the pan off, I checked the red lead at each solenoid and I am getting 12v there as well.

While doing some more looking online, I read a thread that someone stated that if the VSS is not sending signal to the PCM that it could also cause this. Was this an accurate statement? If so it gives me something else to look into.

 

Good call Brother,
Yes, that is very accurate. I've heard that the VSS harness connector retainer clips can become very brittle and will break off when prying up on them to remove the harness from the VSS, and what happens is when the clip breaks off then the harness connector will vibrate out just enough to lose continuity while driving. Make sure the connector is pushed on tight before purchasing a new VSS.
BTW... A faulty VSS and or poor VSS connection can absolutely throw codes, cause non-shifting issues and erratic speedometer. I believe there's more than one VSS on the trans if I'm not mistaken.

 

Went out into the garage this morning and ran all new wiring from the PCM to the trans connector. Also verified Pin E and T showed correct ohm with the vehicle cold (24). All should be well there. I pulled schematic of the gauge cluster and there is only one pin that is shared. It is a pink wire (1020) that gets fed from the PCM. That is reading correctly.

Gauge cluster still shows vehicle is in 3rd all the time and the vehicle only drives in 3rd gear.

I still have to check the VSS, though I do not have my hopes up that the VSS would cause the vehicle to only run in 3rd. That would explain why the speedo doesnt work but I can't see how that would relate to all those codes and the vehicle being stuck in 3rd. All I can think from here is that the PCM is defective. All other bases have been triple checked.