98 blazer cruise and p0740

[FishFind]

Ok here is what I have going on. 1998 blazer 4.3l 4x4

I have a p0740 DTC that is a TCC code
A airbag light that comes on random. Not always on
My cruise control works intermittently.


I have a 1999 s10 that ran good so I am able to try parts from it. I have changed the ignition switch, Multi-function switch tcc solenoid and fluid.

What else can I do? What do all the problems have in common?

Also I noticed that my speedometer is about 4-5mph off of my GPS. My GPS seems to be accurate in my other 2 cars.

[MT-2500]

Originally Posted by FishFind

Ok here is what I have going on. 1998 blazer 4.3l 4x4

I have a p0740 DTC that is a TCC code
A airbag light that comes on random. Not always on
My cruise control works intermittently.


I have a 1999 s10 that ran good so I am able to try parts from it. I have changed the ignition switch, Multi-function switch tcc solenoid and fluid.

What else can I do? What do all the problems have in common?

Also I noticed that my speedometer is about 4-5mph off of my GPS. My GPS seems to be accurate in my other 2 cars.

First thing clear codes and see if any come back.
And post back code no.

Check air bag code when ligtis on and gives us code no.

Cruise and transmission depend on speed sensor.
Air bag depends on good clock spring.
And all three depend on good ign switch.
Check voltage in and out of ign switch.

[FishFind]

only code is the p0740 and it comes back within 2 seconds of being cleared. Don't even shift from park

[MT-2500]

Originally Posted by FishFind

only code is the p0740 and it comes back within 2 seconds of being cleared. Don't even shift from park

We need air bag code hen ligt is on.

On code P0740 get the repair flow chart for that code and work all of the way threw it.

[FishFind]

cruise is fixed. That was the actual unit under the hood.
Ill check the air bag light if I can. It goes on and off again in just a few seconds.

I have the flow chart but I dont have a ODB scanner yet. Can you command the tcc solenoid on and off with a ODB2 reader or do I need a tranny reader?

[MT-2500]

Originally Posted by FishFind

cruise is fixed. That was the actual unit under the hood.
Ill check the air bag light if I can. It goes on and off again in just a few seconds.

I have the flow chart but I dont have a ODB scanner yet. Can you command the tcc solenoid on and off with a ODB2 reader or do I need a tranny reader?

If air bag light flashing on / off it is telling you there is a problem and has a code.
Some you can count flashes for code.
How many flashes long /short or flashes do you have?
You need a air bag capable scanner to to get/read out code and read out air bag data.
To control transmission solenolids you need a good transmision/engine capable scanner which is usually air bag capable to.
Good Luck and.
Let us know how it goes.

Go threw the repair flow chart checking voltage and restance to and from solenoid and wiring and plugins.

[FishFind]

Ok the air bag light.
I started the blazer 2 times. The first time it flashed 7 times and stayed on after the 7th flash.
The second time it flashed 4 times and went off after the fourth flash.

[MT-2500]

Originally Posted by FishFind

Ok the air bag light.
I started the blazer 2 times. The first time it flashed 7 times and stayed on after the 7th flash.
The second time it flashed 4 times and went off after the fourth flash.

Seven flashes and stay on says get out the sir/airbag capable scanner and get codes.

Post back air bag codes.


Air bag repair is best left to the profession trained on air bag repair.
Air bags are like a loaded shot gun they can save your life or take it in a split second.