I have had to change several CPS.
Usually when they fail, they throw a DTCode, and cause no start/hard start conditions, sometimes when you succeed starting, it runs more or less fine, sometimes rough.
This time, we were a bit confused at first glance as the truck was having a PMD issue too, and the CPS failed only few minutes after we swap to the new PMD,
throwing no specific codes.
The only codes we can refer to were the ones about cylinder/injector circuit contribution/balance fault.
What made me thinking about the CPS is that the truck was running like if she was not properly timed.
Changing this CPS doesn't takes long, about 1/2 hour job.
1- don't do it on a warm engine. Your hands will thank you for that.
2- locate the plug, usually hidden under the T-stats housing. Disconnect it and attach a piece of wire 1 meter long to it. Leave it here.
3- Pull out the protection plate under the engine (held by 15mm headbolts)
4-locate the sensor : it is down under on the front of the block, on the driver side, behind-under the reservoir of the power steering pump, inside a hole so it's front end can sit close to the harmonic balancer (aka damper), the one behind the 6 grooves crankshaft pulley.
This sensor has to monitor the revolutions of the crankshaft to report the PCM, and the PCM will then use this information for timing purpose. To do so, there's a notch in the damper wich causes an impulsion each times it passes front of the CPS magnetic sensors.
5- using a 13mm flat wrench, remove the bolt retaining the CPS.
6- now, it's time to have fun. Pull out the CPS. If you are lucky, it will come out.
If like me, you are working on a lowered suspension truck, laying under the engine, with light in the eyes, cause it's late and night has come, I'm sure you will wonder what have you done to God to merit this : CPS sensor was stuck. A few WD40 later, it comes out... and found that this funny power steering pump reservoir just decide kidding you and won't let you have enough place to completely remove the sensor.
Few cursing words and a beer later, you figure you get choices :
a - leave the CPS here and tell the guy lighting a match in the engine could solve all problems,
b - remove serpentine, remove power steering pulley so you can release enough the power steering pump (yes, ask the GM engineers why do we have to do all that just to access the bolts retaining the power steering pump)
c - drink a second beer and think.
Finally, I choose the c
So, after the second beer and before the 3rd, :idea: : with the agrement of the owner, I slighlty hammered the reservoir, so I can get just enough place to extract the CPS.
7- put the new one in place, bolts, protection plate, using the piece of wire which came with the old harness, attach the new one, fish it to the top and connect.
8- wash your hands, finish the 3rd beer, smile to the owner who's looking at you anxiously, and start the engine.
9- do time set;
10 - enjoy, and no, don't take that 4th beer. 3 is enough
hmy1: I've never heard an engine screaming like that !!! It was like if the engine was alive, it was like a live pig you're trying to cut the throat of
