2005 Jeep CRD 2.8

Danno150 · **Joined:** Fri Jul 19, 2019 4:10 pm **Posts:** 19

Just heard from my Mechanic. There's no power going to the Crank Sensor, believes the problem is within the ECU. He admits he's not a electronic specialist. Would need yet another tow to the guru I already talked with that did not want to look at it.

Billybob · **Posted:** Sat Aug 03, 2019 6:32 am

Danno150 wrote:

Just heard from my Mechanic. There's no power going to the Crank Sensor, believes the problem is within the ECU. He admits he's not a electronic specialist. Would need yet another tow to the guru I already talked with that did not want to look at it.

He is correct in that he is not an electronic specialist!

If you look at page 8W-30-27 in th2005 Jeep KJ Service Manual you will see the Crankshaft position Sensor at the lower-left of the page.

There are only two wires going to it.

The Brown/Light Blue wire goes from pin #2 on the sensor to pin #88 on connector C1 of the ECM.
The Dark Blue/Brown wire goes from pin #1 on the sensor to pin #87 on the ECM.

There is no power being supplied to the sensor...this sensor is effectively a coil of wire wrapped around a metal core.
When the marks on the crankshaft pass over the sensor a sine wave will be generated that the ECM picks up.

So assuming that you have a nice new, good quality Crank Sensor fitted:

Disconnect connector C1 from the ECM...you have normally have to pull up a tab on the connector then the connector pops out. First disconnect the battery completely!
This now means that the sensor is not connected to the ECM.

Now disconnect the sensor itself.

With a digital Multimeter set to read Resistance ie. on the OHMS setting, place the meter leads across the sensor's two pins...make sure that you are not touching the leads with your fingers or your body resistance will affect the reading.
The reading should probably be around 30 Ohms or so...I am just taking a wild guese here!
If it is 0 to about 3 Ohms it is probably short circuit.
Compare these readings to the old sensors you should have lying around.

At this stage with the sensor disconnected and ECM connector C1 pulled off.....the two wires going from EC to the sensor should be floating in fresh air.

Measure the resistance between the two wires ie. where you disconnected it from the sensor place one meter lead on on the Brown/Light Blue lead and the other on the Dark Blue/Brown wire...do not touch the leads with your fingers!
Repeat this at the other end of the lead ie. at the C1 connector.
There should be no reading at all ie. infinity if the two leads are not shorting to each other.

Now take off one of the leads and place the lead to engine/chassis.
There should likewise be no reading at all unless this lead is shorting to ground.
Do the same with the other lead to check that the other lead is also not shorting to ground.

If you do not get a complete open circuit reading with the two last tests above ie. the meter shows maybe about 30 Ohms to 1,000 Ohms then the lead is not shorting to ground but shorting to another random wire somewhere in the harness...pretty much hard to trace.
In the KJ although this sensor may be physically located about two feet from the connector C1 on the ECM it does not always take the shortest route. On my 2002 Export CRD the wires all go around the whole engine bay ie. about 8 foot if harness!
Try to unwrap these two leads to the sensor from the harness to see if you are lucky and it is a short trip and you have the two leads hanging in thin air.....this way you can see if these leads are shorting together or shorting to ground or to another wire somewhere.

Now check with your meter that neither of these two leads are open circuit ie. place the one meter lead on the Brown/Light Blue wire at the sensor end and the other meter lead on the same wire at the ECM connector C1 pin 88.
You should get continuity here if the lead is not broken.
The wiring diagrams show the way the pins are numbered on the C1 connector so you should be able to find the correct colored wire at the C1 connector. You may need to tape a pin or needle to this meter lead to be able to get into the correct hole or else pierce the wires insulation with the pin/needle to get to the copper wire below it.

Repeat the above procedure with the Dark Blue/Brown wire

If you find that either of these two wires going from the sensor to the C1 connector are either open circuit or are shorting to ground or some other wire you have to do the following:

You have to cut off both ends of the suspect wire a few inches from each end and wrap some tape around the cut-off ends. Now take a new piece of wire and connect it to the short pieces of wire that you left at both ends...insulate them neatly. If this lead is not a short section but travels around the whole engine bay then rather take a short cut ie. connect to wiring direct from the sensor to the C1 connector taking the shortest route.

This is pretty complex to anybody not familiar to wiring like this but it needs to be done by yourself or an Auto Electrician if you have bad wiring......replacing the ECM will not fix the problem if the wiring is bad!
So take this description of mine along with a printout of page 8W-30-27 to an Auto Electrician!

I have recently done this procedure for the tenth time on my 2002 CRD due to ten wires being broken/shorting somewhere inside the long main harness. These problems mainly due to a front-end collision! :shock:

Danno150 · **Joined:** Fri Jul 19, 2019 4:10 pm **Posts:** 19

Billybob. Again thanks a bunch.
The info I retained is obviously wrong. I had read earlier that the 2 wires should carry 5v (key ahead) and produce a reading of around 3.4 ohms when key turned off.
This headed me, and likely my mechanic in the wrong direction. This would be my fault.

Dan.

Billybob · **Posted:** Sat Aug 03, 2019 3:18 pm

My long post above was to help owners trace down any wiring problems before replacing components one by one.
It is serious stuff for owners not into climbing this deep into wiring problems but I believe that as these Jeeps get older then there will be more cases of wires grinding through to engine/chassis or to other wires in a harness or suffering a break! :shock:

Danno150 · **Joined:** Fri Jul 19, 2019 4:10 pm **Posts:** 19

Billybob.
Already printed off for my Mechanic/ Electrical guru, will keep you posted.
I had a brief chat this a/m. He had a buddy electrical dude stopping in this afternoon to have a look see.
I explained, best I could, over the phone of the suggestions to follow.

GordnadoCRD · **Posted:** Sun Aug 04, 2019 4:02 am

Keep on pluggin away.
Details are important.
I've been misled by errors in the FSM nearly as often as I have by knowing the FSM has errors, and assuming I've found another one.
Fortunately most of the time I've had access to this pool (LOST) of knowledge and experience to help me through.

Danno150 · **Joined:** Fri Jul 19, 2019 4:10 pm **Posts:** 19

Part 6- Week 8 "Resolve"[b][/b]
Crank Shaft Sensor.
Very long drawn out story cut way short. Vehicle on second Mechanic and 2 tows. Moe (second Mechanic and tow) had agreed to look at the Jeep and it was understood that due a weeks closed from vacation and returning to 20+ batteries missing from customers vehicles, he'd get at it when he could. Where another Mechanic had been under the hood etc., basically he had to start again. The Jeep which would start and run for a brief period prior in a/m cool weather, now would not run at all. It did, still manage to throw a code without starting. Crank sensor.
I had purchased a new OEM Bosch sensor ordered in (Dealer part) as well a few $'s less than NAPA and had included this to the first Mechanic that didn't have time in 2 weeks it was there, to replace. Moe had a good scanned (yes there are the dollar store variety and those that go a bit further). While cranking it threw the code. Part replaced after other testings, fuel etc., (second new one) and the Jeep fired in 2 cranks as it should have.
I trust and hope that those that followed here understand in comparable parts, in particular those to Dodge/Chrysler/Jeep. I had been forewarned of this after my original purchase of the NAPA/ China replacement. Lesson learned. Whether the part is actually incorrect/incompatible or due mass production, junk from the box, I'll likely never know.
Very special thanks to those that followed along and took the time, and in detail, (Billybob and Gord) to help out. I hope this venture will help out in future.
Cheers!.
Dan.

WWDiesel · **Posted:** Thu Aug 29, 2019 3:51 pm

Glad you got it figured out and that fixed it! :BANANA:

As an old mechanic, I have had on occasion several times had brand new parts, especially electrical, right out of the box that were bad.
Very frustrating and time consuming to say the least! :banghead:

As to the crank sensor, I don't know about the NAPA part, but as I have posted many times, if you have a AutoZone store near by or you can order on line.
They have a reboxed Bosch OEM crank sensor in their Duralast line:
Duralast Crankshaft Position Sensor SU8492 (Bosch PN 0281002434) ($89)
I have one of them in my Jeep CRD currently and it has been in there since about 2014 with no problems.
Maybe this will help someone from encountering the problems you ran into and save a few bucks as well?
https://www.autozone.com/engine-managem ... 793836_0_0

Danno150 · **Joined:** Fri Jul 19, 2019 4:10 pm **Posts:** 19

Most unfortunately part of the problem is when ordering outside the Dealer, few, very few, have any idea just who the actual supplier is. In hand is one thing, ordering, quite another.
Very time consuming yes. In this case at least, quite unnecessary.

WWDiesel · **Posted:** Thu Aug 29, 2019 9:27 pm

Danno150 wrote:

Most unfortunately part of the problem is when ordering outside the Dealer, few, very few, have any idea just who the actual supplier is. In hand is on thing, ordering, quite another.
Very time consuming yes. In this case at least, quite unnecessary.

That is why I can recomend the AutoZone part, I know whats in the box. At least is was in 2014, I hope that is still the case.
Finding an OME Bosch part in a reboxed part for about half the price of a Mopar part is good information....

2005 Jeep CRD 2.8

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