Turbo/super boost sensor???

[gsroseberry]

I've recently purchased a 98 CK 3500 from a relative. the truck has had the SES light on for years and after taking the truck to Autozone and having the codes read, only one code was tripped. "P0236 Turbo Boost sensor A ckt" is what the scanner was reading. go figure autozone doesn't carry the part, know what it looks like, or where it is located. I checked with O'riely, Advanced, and CarQuest as well but none of them carried or knew anything about the sensor either. I also checked with a local dealership and they were unable to locate the sensor in the computer sensor. When I asked a mechanic where I could possibly locate the sensor under the hood his only response was "by the turbo..." does anyone know where it is located on the truck, where I could find a new one, or what it even looks like (electronic? vacuum?)?:confused:

[DennisG01]

That code could come up for a few reasons. Here's a few things to get you going:

When it happened to me, the Wastegate Solenoid was bad. It's a somewhat common part to fail - luckily it only costs about $35. It is located on the driver's side of the air intake, towards the firewall. Follow the vacuum line from the wastegate (the "can" that sits on top of the turbo and has a metal arm sticking out the bottom) if you're not sure. The solenoid will have two vacuum lines coming out of it (the other one connects to the vacuum pump). The vacuum lines could also be leaking. At idle, you shouldn't be able to move that "metal arm". With the engine off, it should move easily

However, first thing to do is clear the code and see if it comes back - sometimes the solenoid sticks. Autozone should be able to do this - even with a generic scanner.

Actually, the easier first thing to do is: When you accelerate hard, you should only get a puff of black smoke until the turbo spools up. If you are getting a lot of black smoke, then more than likely something is wrong with the turbo system. If you are not getting black smoke, then the turbo system is probably fine.

Do you have a boost gauge? That (and an EGT - especially if you're towing) are good gauges to have. Also a Tranny Temp gauge.

[diesel65]

Check that the vacuum pump is working, you should have a minimum of 20 inches of vacuum at the wastegate solenoid.

[DA BIG ONE]

It's located on top of the intake manifold looks like a MAP sensor black in colour, w/2wire hookup and also has a port under it that taps into intake. You most probably have a bad one since your popping that code.

[gsroseberry]

thanks. i am getting thick black smoke at all times when i accelerate. i checked out the wastegate and i was able to move the arm freely both with the engine running and off. would this indicate a faulty wastegate solenoid, or a vacuum leak? or are both a possibility?

[diesel65]

Again, check that your vacuum pump is working.
If you don't have vacuum at the wastegate solenoid then you need to determine if the pump is bad or you have a broken vacuum hose from the vacuum pump.
After you determine that you do have vacuum, then you can look and see if the solenoid, wiring or vacuum hose after the solenoid is a problem.