Shownomercy

iTrader: (1)

Running a vortec dizzy for cam position signal, and it is throwing a CMP code. I want to verify my wiring before running some tests on the sensor and then calling EFIconnection to ask for a potential warranty replacement.

Starting with how the regular LT1 24x cam sensor should be wired.

Red (A) Ignition Hot 12v source - Red 39
Pink (B) Ground source - Blue 61
Brown (C) Signal - Blue 73

Assuming they are right, I then took them and feed the Vortec harness as follows

Blue 73 -> Brown/White (B)
Blue 61 -> Pink/White (A)
Red 39 -> Red (C)

How bad did I mess that up?

S10Wildside

You have it wired correctly:

• A: PNK/BLK - Low Reference
• B: BRN/WHT - Signal
• C: RED - 12V Reference

To determine if the sensor is working, monitor the two cam sensor PIDs through your scan tool:

• CMP Low to High
• CMP High to Low

Let us know if they are incrementing - one after the other.

Might also be a good idea to check there are no breaks in the wire harness from the CMP sensor to the PCM.

Shownomercy

iTrader: (1)

Checked and had good ground, good hot, good continuity for pcm signal lead.

Codes are being thrown for low and high

S10Wildside

What are the CMP PIDs showing you? Are they incrementing during engine rotation?

Shownomercy

iTrader: (1)

Engine is untuned and does not run, so really can't check the running PIDs.

Was going to check via hand cranking and watching signal for correct 12v pulse on voltmeter.

S10Wildside

You can crank the engine and monitor these PIDs. The engine does not have to be running.

Shownomercy

iTrader: (1)

So, the PIDs look to be working, the numbers follow each other as far as HPtuners showed.

That is with a new cam sensor in there, so, looks like the dizzy was installed out of sync?

Is there anything that can be done to minimize the amount the PCM relies on the CMP signal?

S10Wildside

This indicates a good cam sensor (and signal).
No. Consider what it does. The PCM can only know crankshaft position because of the 24x encoded pattern from the crank reluctor/sensor. With that information alone, it has no way to know which stroke the engine is on (intake or exhaust). It would be silly to minimize the importance of the cam signal because then the PCM would have to guess if a given cylinder was on the intake or exhaust stroke. Ignition timing and fueling depends on this information in a critical way.

Shownomercy

iTrader: (1)

That only applies to starts though correct?

Being as the engine needs to come out to reset the CMP position, I will hope the tuner can get it running well and live with rough starts till I either drop the motor or just buy the regular LT1 cam sensor from you.

duh

iTrader: (16)

I would think that you can drop the k-member a few inches to facilitate the re-timing of the dizzy. THe hardest part is making sure you can see the mark on the dizzy body and then making sure where the rotor would line up with it at #1 TDC. Speaking from experience with the vortec dizzy, even if you're a tooth off it causes the vehicle to run like junk. I can only imagine that it would do the same and cause nothing but issues with the 24x. It's probably more worth taking the time to do it right then risk screwing up everything because the sensor is off and causing the PCM to try and do things it shouldn't. That's just me though.

S10Wildside

This can be avoided by using an oscilloscope.

No. Consider the application. When the Vortec distributor is used to deliver spark, orientation is critical because being a tooth off means the rotor is now out of phase (mechanically) with the engine. In this case, the engine will run poorly. But when the Vortec distributor is used as a cam signal (no rotor involved), the PCM allows forgiveness up to 8 degrees either direction of camshaft centerline.

duh

iTrader: (16)

I understand completely now, my headaches came more from the cap and rotor being off than the cam sensor being out if whack. I thought it was the other way around since rotating the whole distributor body did absolutely nothing to help the way that truck ran. Makes sense now.

Shownomercy

iTrader: (1)

Does anyone have a good install guide for using the vortec dizzy as a 1x signal?