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91-92 CPS?

ehall

NAXJA Member
NAXJA Member
A buddy with a 91 YJ is having no-spark trouble so the obvious thing to test is the CPS right. I know the basic HO test for infinite resistance on pins B and C, but when he looked at the connector he found that it's the round style like on the RENIX XJ not the oval style. I got to thinking well maybe it actually is the RENIX sensor, and they were just reusing parts on the Wrangler, so I check rockauto and it says 91-92 for the YJ *and* the XJ. Now I'm really wondering so I go look at my XJ and lo it has the round connector.

Alright the form factor is weird that's all, and interchange does NOT show 87-90 so it's probably a different sensor just in the old-style form factor. So I check the FSM and it lists the RENIX style tests, IE check for 200 ohms +/-75 ohms on pins A and B, instead of the new-style test of checking infinite resistance on pins B and C. So it's the RENIX test, but and the RENIX form factor, but not the same sensor!

Now we're like okay we still don't know shit but let me test my CPS and we'll figure out if it's working then go from there. So I test all of the pin combinations and get infinite resistance everywhere. According to the FSM my jeep should not run... My assumption now is that the FSM is wrong and has the RENIX-era test procedure when it should have the HO test procedure since that is how mine tests out (infinite on all pins all the time). This isn't the first error in the FSM, and the resistance charts for the CTS and MAT are also for the RENIX-era sensors and not for HO sensors.

This is pretty confusing. The sensor connector is round like RENIX, but the sensor does not interchange with 87-90. The FSM shows the RENIX tests, but it does not pass those tests and instead passes the later-year HO tests, or I am doing the tests completely wrong.

Does anybody know WTF is going on here
 
The two wire CPS is Renix, the three wire CPS is for later models as far as I know.
 
I didn't think about that. Just checked rockauto, the RENIX is 2-wire with a 3-pin GM weatherpack connector (same style as the MAP sensor), so it is completely different from what we are looking at. I guess the 3-pin for 91-92 is specific to this series, and therefore ought to be using the HO tests (meaning the FSM is wrong)
 
I noticed that also, the FSM's using data/info from the last XJ series for the newer model. Noticed some V-6 info for motor in the early Renix FSM and even some drive line stuff from FSJ's in there.
 
I think the CPS, or at least the connector, is unique on the 91. According to Haynes (yeah, I know, but I don't have better for this one) you should check between terminals A and B and see no continuity, rather than between B and C as in later models.
 
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