Code Help for my 87 K5 Blazer

[87K5BLAZER]

I have had an issue lately with the Service Engine Soon light coming on when I am accelerating up hill or on the freeway. This only comes on after driving for about 15 minutes or more. Once on the light stays on but will not come back on if the motor is turned off then back on until it is under the same situation. I borrowed a Snap On code reader and came up with a "43 ESC MODULE OR SENSOR CIRCUIT PROBLEM." From my research so far it seems to be a Knock Sensor. I have read ways of testing it but I'm thinking of just replacing it.

The truck is an 87 Chevy K5 Blazer (stock) with a 350 TBI, 700R4 trans, NP205 transfer case and GM 10 Bolt axles. The only thing not stock on the drive train is a K&N Air Filter.

I was wondering if the Knock Sensor would also affect the tranny with regards to down shifting or shifting into over-drive? This also occurs after about 25-30 minutes of driving. The trans was rebuilt about 3 years ago and doesn't have more than 1500 miles on it. I service it more than regularly before almost every 4 wheelin trip.

I am not a technical mechanic so please try to reply in not so technical terms. Any help to resolve this issue is appreciated. I need to smog the truck before January so I need to fix it soon.

Thanks,
Robert
87K5Blazer
 

[moorehouse77]

Do you have a volt/ohm meter and if so do you know how to check for ohms?


Dave.

[lqcj8]

as far as trans problem, what size tires are running? with bigger tires and stock gears you could have a shifting problem

[87K5BLAZER]

I have a volt/ohm meter and I'm going to check that tomorrow.

As for the shifting problem, it only does it after the truck has been driven for about 25-30 minutes. I was thinking it might be a vaccum issue. I am running 35" Goodyear Wranglers. It has 383 gears.

[moorehouse77]

Yeah check the ohms between the terminal on the knock sensor and the engine block.  Should be between 3,500-5,500 ohms. 


Dave.

[87K5BLAZER]

Okay, so I changed the Knock Sensor and first was suprised to find out that when removed, water/anti-freeze began to flow out. I installed the new sensor and connected the wire and checked for error codes and still got a 43. I then checked the ohms with 2 different testers and neither one got a reading. Now does anyone know where to start with fixing that issue. The Chiltons book described the problems I have been having under a load and also said that it will affect shifting. Thanks for everyones help so far.