When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Any good/reliable aftermarket 4.0 crank position sensors?
Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!ZJ (93-98), WJ (99-04), WK (05+)
All ZJ/WJ/WK specific tech questions asked here!
I haven't decided whether to pickup an OEM or not as my current cps is working fine without any problems.
I now have a spare backup Napa Echlin for for the ZJ. I haven't changed the ZJ 4.0L CPS only a 98 XJ 4.0L cps so I'm not certain if it's any more difficult.
When changing the XJ 4.0L cps it was more tricky than difficult. I just need to move and angle the extensions and socket adapters just right, being careful not to drop the bolt(s) inside the bell housing. It's sort of tedious but I think if you took the time to practice or did enough of them it would become easier.
I can remember some people creating an access hole with plug or plate, near the cps for easier access.
What happens with some of the aftermarkets is their magnets are weak and have problems detecting the fly wheel notches.
The cps on the Jeep 4.0L are a halls effect sensor that pulls to ground. I found a diagram online however it shows a reference signal of 8 volts. My 98 XJ OBD2 uses a 5 volt signal so I guess at least some earlier Jeep 4.0 uses 8 volts vs 5 volts to drive the sensors? My PCM for the 98 XJ I remember has a 5 volt power supply for it's sensors. So the 93-95 ZJ 4.0L PCM must have an 8 volt power supply for 8 volt sensors? I'm still becoming familiar with the 95 ZJ which imo has at least a few significant improvement over my 98 XJ.
NOTE: The below crankshaft position sensor wiring diagram applies only to 1993, 1994, 1995 4.0L Jeep Grand Cherokee.
From what I can remember these hall effect sensors use a small transistor to send a ckp signal to the PCM using a magnet that detects flywheel notch position. Also an open area on the flywheels allows the PCM to determine a reference position of the entire crank shaft. I believe one of the primary reasons why most of the CPS fail is due to heat. (high temperatures) As they age won't work or work correctly when there is too much heat. So perhaps the OEM's have a different temperature rating? or better insulated? using a better quality transistor and wires? I don't know, haven't cut any apart for a comparison.
It was mentioned previously that the engine had to be allowed to cool before it could be re-started. This makes the case for the heat factor affecting internal resistance in the transistor and dropping signal voltage to the PCM, if the magnet were weak I would think the engine would run poorly at cool down as well as operating temperature, conversely, I would think a weak transistor in a malfunctioning CPS would allow the engine to run ok when cool, becoming progressively worse as it reaches operating temperature because of increasing resistance. I try to get out in front of potential problems by considering the age and miles on sensors, the used one going in the spare parts box just in case...
The magnet in the OEM IMHO is 90% stronger than the aftermarket parts, apparently made from unobtainium. Compare them someday when you have a few minutes to waste. I've been there, done that and don't wanna do it again. It's probably the only part you'll want to stick with OE when it comes to the 4.0 because of the location, contortions required, running out of expletives and people to blame during the process. Yes, the one holer is for the 4.0 WJ.
From Napa, the Echlin CPS has been in our ZJ for past two+ years, 140000km, no problems (other than the difficult to reach access to the bolt).
Long , long ratchet extensions are your friend in this fix.
Prices in 2016 Napa $75 Cdn, Jeep Dealer $110 Cdn
Some times our dealers parts counter buys the part from local suppliers (Napa, Car Quest, APC, etc) and marks up and resells. I have not always received a Mopar branded part.
All the best with your OEM Cps!
02-19-2019, 08:56 PM
