Still working on my 94 Blazer. I have new codes 34 so I replaced the MAP sensor, 42 Electronic spark timing or fuel cutoff relay circuit, also 72 Gear select switch or vehicle speed sensor. it started blowing a fuse that would shut down the fuel pump and maybe the computer as I could not pull codes till I replaced the fuse then it would start again. It then ideas fine but as soon as you put it in drive it starts dropping off like the injectors are not working or losing spark it came home on the flatbed again any ideas. This is why I love my 70 K-5

 

Well... Do you think that any of this has anything to do with your previous thread from earlier this month? If so, I can combine them together.

As far as the code 72 goes, does your speedo work? If so, your VSS should be good, but it may have an intermittent connection that is triggering this code. If the VSS is dropping out, it will cause transmission problems. You may want to pull the VSS (transmission tail shaft if 2wd or transfer case tail shaft if 4wd) and give it a good cleaning.

For 34, did the replacement MAP sensor fix this code?

And 42, this code description for the 93-95 Vin W OBD1 vehicles is actually "The EST signal did not change when the ECM applied bypass voltage to the ignition module." This sounds like you have a problem with the EST module. This could definitely cause the symptoms you are experiencing.

 

Thanks now where is the EST Module located. Also where is the inertia switch located on this model

 

Inertia switch? For what? Are you talking about the VSS sensor? If so, that is located in the tail housing of either the transmission (if 2wd) or transfer case (if 4wd).

The EST module is located in the base of the distributor. It is what the two plugs plug into.

 

Thanks I might as well replace the whole distributor as it looks rusty inside as for the inertia switch that shuts the fuel pump off in a accident I have heard of them going bad and intermittently shutting off the fuel pump I am not use to all this injection stuff

 

The inertia switch is on newer and higher end cars. They usually have a curcuit breaker style switch in the truck to turn the pump off. I dont think blazers have this, certainly not these older ones.

 

Thanks I have the new distributor and should have this on Friday hopefully this will solve the problems and my blood pressure can return to normal thanks for the help