I am having a problem with Trans codes only when I remote start my Blazer. I have been working this for some time.

The following codes only come on when I remote start the blazer.
P0740
P0785
P1860

I know what the codes are the part that puzzles me is why they ONLY come on when I remote start it?

After examining the harness under the colume I found a heavy guage Brown wire that shows 12v+ in "accessory" and "run" positions only.

Does anyone on the site have wiring schematics for a 1997 4Dr S-10 blazer and can tell me what this wire operates?

Even if you can give me an idea what it may operate. Any help would be muchly appriciated.

THanks in advance

P0740 Torque Converter Clutch Circuit Malfuction
P0785 Shift/Timing Solenoid Malfunction
P1860 TCC PWM Solenoid Circuit Electrical

Usual cause, ignition switch.

If it only happens with remote start, it's because you are powering up the PCM to start, but you're not powering up the transmission. If it was being caused by the ignition switch, remote start wouldn't be a factor.

If you can give me a reference for the brown wire, I can try to get the information for you. Where is the connector located at? How many wires in it? What are the other wire colors?

The transmission is computer controlled through the same ECM that controls the engine.

You have to very very careful how you hook up the remote start on your vehicle, The ignition 2 wire needs to be powered during starting and run positions, most remote starts default to ignition 2 off during cranking. Check out this link.

http://www.designtech-intl.com/Content/techsupport/documents/section04/note128.pdf

Regardless if the transmission's computer is controlled by the same computer that the engine is controlled, the transmission also requires other outside power sources for certain circuits to operate.

This is evident by the fact that people who actually do have an ignition switch issue that causes transmission related codes, can generally still start and drive their vehicle.

Hi all, thanks for the replys thus far.

I have already replaced the ign switch due to an earlier post and other information I have found on the web. The ign switch includes the wiring harness that runs from the key down to a block at the lower of the steering colume. The brown wire I am refering to is the brown wire in this harness. Its a pretty good size, the same size as the yellow one that operates the starter cercuit in the same harness. Slightly smaller than the Red wire that feeds the power to the switch. Not really sure how else to describe it. except its maybe a 12 Guage wire that runs from the ignition switch to the block at the bottom of the steering colume.

normal operation works normally with no error codes at all. I can start and operate the truck normally. However when I remote start the vehicle about 7 to 10 seconds after its been started the check engine light comes on and about 1 min after I start driving the transmission starts to slip in first gear. If I pull over and reset the computer I can start it with the key and the truck goes back to normal operation. This is a reproducable problem and will happen every time.

I wish I could help, but I only have a '98 manual and I'm not sure if the 97/98 changed any wiring.

I recall two brown wires when I looked at my book lastnight. Only one was I able to trace in the book at the time. It goes to the fuse block under the hood. It powers the clock/radio, power windows, and a few misc other things. I did not see any transmission related items on that circuit, but it could very well be there and I didn't see it.

I would agree with ricksza, who seems very knowledgable. I think you have atleast 1 circuit that isn't being powered up with the remote start, which in turn is not allowing power to the transmission's circuits that require power to properly communicate with the computer as well as operate the transmission.

Here's the power supply to the transmission that has to be powered with the remote start:

http://files.automotiveforums.com/gallery/watermark.php?file=/500/131561trans-med.jpg

Bingo, Bingo, Bingo

quote "I would agree with ricksza, who seems very knowledgable. I think you have atleast 1 circuit that isn't being powered up with the remote start, which in turn is not allowing power to the transmission's circuits that require power to properly communicate with the computer as well as operate the transmission."

Got to looking at this last night and started tracking wire by wire. The remote start I have installed id a Viper 791. It has a remote relay Pack with a sub wiring harness that fingers into the Ign harness under the colume. There is a control Ribbon cable that runs from the brain of the unit to the remote relay Pack.

Anyway I tracked it wire by wire checking first the control harness then a friend of mine suggested a weak relay. So as I was checking the output harness found a bad connection inside the plastic connector. Looks like it never got snapped properly into the plastic connector from the factory.

Anyway, took it apart, got the connector back together properly and now... NO MORE CHECK ENGINE LIGHT!!!!

Cannot believe it but sure glad its gone. Thanks for all your input. Espically the note from design tech, got me to understand the wiring little better and finally leading to the problem.

Thanks all, again I appriciate the help