P-pump & electronics

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OilfieldOutlaw

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Jul 7, 2019
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I just spent the last 2 hours reading about p-pumped 24valves. There is a vast amount of information on this site! I am curious about how the sensors work after doing this swap. I just purchased a 98.5 that has been p-pumped and I currently have no tach or AC. After the last 2 hours I now know that the 2 are related, but I'm wondering in what way? Could someone explain the relationship of a crankshaft sensor to AC & the tach?

I plan on replacing the crankshaft sensor for piece of mind, after replacing battery terminals everything else seemed to start working again. I don't know about if everything is accurate, but after an hour or so of driving the gauge cluster finally seemed to work properly.

If a new sensor doesn't fix the issue, I'm jot sure what the issue would then be.

Thank you in advance!


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In basic layman’s terms, the crank sensor provides the signal to the tach AND tells the PCM that the engine is running. The PCM commands the alternator and the A/C on when it senses the engine is running.
 
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Thank you, what other nuances are to be expected in doing a p-pump on a 24valve? I feel like a kid learning something new. I didn't realize so much of the electrical system was unnecessary, unless you want gauges to work.

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It was born an auto, but now has a G56 manual.
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I believe you'll be fine just replacing the crank sensor. The 24V APPS would come into play if you had an auto.

You will always have a CEL since the VP44 is gone.
 
Went to the parts store, bought a CPS for a 24V, pulled the starter and there was a plate where the sensor would be. Got to poking around online, saw a sensor for a 97/98 12V and verified on my truck that I do indeed have a 12V CPS/ESS.

This truck confuses me.
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That looks to be an 01-02 block that doesn't have a tone wheel on the crank. Need to pull that plastic and see if there's a tone wheel in there. If that's the case then someone tried using a 12v damper and sensor which will not work because the ecm is looking for a 36 -1 signal.
 
Tach doesn't bother me too much, AC does. It was 104 today in west TX.

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Sounds like you’ve got a Frankenram. Get us the number off your PCM. We can tell from that if you have a PCM for the ‘98 12V or the ‘98.5 24V. The 12V PCM gets all it’s info straight from the sensors. The 24V PCM gets it’s info from the ECM which gets it’s info from the sensors. That ESS for the 12V will not work with the 24V PCM to make your tach, alternator, and A/C work.
 
For what it's worth the alternator seems to be functioning. I drove it 45 mins to the house after buying it, a week or so later I fired it up and drove it around town for a bit. Then after sitting 2 weeks, I replaced passenger side battery terminals and it fired up just fine again, I drove it around maybe a total of 45 minutes with no issues.

Here are pics of the pcm
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So, I assume the sensor is bad and theoretically replacing it should fix the tach/AC issue?

A 98 12V with a 5 speed... Wtf lol

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No way anyone could say that for sure. WAY too many variables here. It all depends on what the PO did to it.

That said, yes, IF that ESS is bad, IF that’s the only problem, IF the PO did it right, it SHOULD fix the tach and the A/C.
 
I'm in on this...and you boys wanna know why I put up with the vp...lol..this is why
 
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