Ignition switch

sfcl · **Posted:** Tue Dec 06, 2016 10:30 am

Thanks. I will check again but all fuses and relays were ok, SKIM also (the light goes off after 1 or 2 seconds).
And even if the PCM doesn't receive the signal, the starter should spin...

WWDiesel · **Posted:** Tue Dec 06, 2016 2:03 pm

Given, the Starter Relay (SMR) is good and the starter motor is good,
you say that when you jump terminals 30 to 87 starter motor engages and spins motor over OK

Troubleshooting the Starting circuit using the FSM WD, a check off list: eliminate each one:

DO NOT RELY ON LOOKS

(* also supplies running voltage to ign. sw. terminal 9)

DO NOT RELY ON LOOKS

(** supplies starting voltage to ign. sw. terminal 1)

(***Ground is supplied by ECM provided all other conditions required are met - SEE #1A BELOW)

#1A - Conditions required by ECM to allow the SMR to energize:
Transmission must be in either the "Park" or "Neutral" shifter position.
One or the other conditions must be met and a signal received by the ECM from the shifter switch which allows the SMR to energize when 12v is applied to terminal 86 of the SMR from the ign. switch start position circuit (ter. 6 @ ign sw.)
If Park/Neutral position switch is faulty or misadjusted, adjust or replace park/neutral position switch as required.

Hope this helps?

sfcl · **Posted:** Tue Dec 06, 2016 2:15 pm

Many thanks, great help, I will check tomorrow.
I forgot to mention that this is a manual transmission so only a switch on the clutch pedal (but I would think that the starter motor would spin even if the switch is faulty?)

WWDiesel · **Posted:** Tue Dec 06, 2016 2:28 pm

sfcl wrote:

Many thanks, great help, I will check tomorrow.
I forgot to mention that this is a manual transmission so only a switch on the clutch pedal

(but I would think that the starter motor would spin even if the switch is faulty?)

Not so, there are two different circuits from the Clutch Interlock Switch feeding into the ECM and they have to be satisfied (clutch sw. in correct position) before the ECM will supply a ground to terminal 85 on the SMR..

I really wish we had access to a ECM Control Logic diagram, it would help much in diagnosing certain problems... :banghead:

sfcl · **Posted:** Tue Dec 06, 2016 2:33 pm

Interesting, this would explain why I get 12V to the solenoid wire terminal while the starter still doesn't spin...

Some checks to do tomorrow! Many thanks once again!

sfcl · **Posted:** Wed Dec 07, 2016 9:34 am

Soooo.... the story continues...

I have made all tests (thanks again!):

- Check fuse 28: I have no fuse 28 on this vehicle, but I get 12V to the 86 terminal at SMR when ignition switch is on "start". So should be ok (I get 2.8V when ignition off though)

- Fuse 8: Ok

- Fuse 14: OK

- Checked again all the continuities at battery cables.

- Ground signal to 85 terminal at SMR when ignition switch is on "start": I get 6.8 volts all the time to this terminal since the key is on "On" or "start", clutch pedal depressed or not (0 V if ignition switch is on "off"). Seems something is wrong here??

I have also tried to ground the 85 terminal (putting a wire between this terminal and the - terminal of the battery) With that, the starter motor spins (clutch pedal depressed or not) since I put the ignition switch on "Start" but the engine still doesn't start.

So the problem is not only to energize the SMR but also to start the engine. I'm not 100% sure but the clutch switch seems ok as the starter solenoid clicks when the ignitioo switch is on "start" and the clutch pedal depressed?

WWDiesel · **Posted:** Wed Dec 07, 2016 12:49 pm

OK, manually grounding terminal 85 and then the starter motor engages and spins the motor over tells me the problem is your ECM is not satisfied..
The big clue here is that the engine still does not start with the ign. switch in the start position when terminal 85 is grounded...
When the ign. switch is placed in the on or start position, it powers up a lot of things.
It appears in your case, the ECM is not getting a required condition from one of the inputs to allow the engine to start.
Is the ASD relay energized when the ign. switch is placed in the on position?
Have you tried swapping the ASD relay with one of the other relays?
Check fuses no. 6 & no. 26, 6 supplies 12v to the ASD relay, 26 supplies 12v to the ECM via the ASD relay when it is energized.

Are there ANY DTC (codes) set when you scan???

sfcl · **Posted:** Wed Dec 07, 2016 1:53 pm

No code at all! I would have preferred to get one to have at least an indication...

I was just trying to swap the ASD relay when I now notice that the starter solenoid doesn't even click anymore while trying to start... Pfff, need some rest, will try to recheck everything tomorrow.

Once again, thanks for the help!

sfcl · **Posted:** Fri Dec 09, 2016 8:57 am

Update on this problem.

Now the solenoid doesn't even click. Still no default codes. I tried to check the clutch pedal position but it seems that a major part of the dash has to be removed to get it!
I reckon that I don't know what to do now, maybe a fried PCM, and having no Jeep specialist around here doesn't help.

Noticed also that the battery (brand new) drops its voltage in one night (12.6 to 12.1 in 12 hours).

I think I have done all checks with no results, I will try again before selling the vehicle for spare parts...

WWDiesel · **Posted:** Fri Dec 09, 2016 10:15 am

Change the electrical part of the ignition switch!!! :idea:

sfcl · **Posted:** Fri Dec 09, 2016 10:22 am

I did it already. And all current arrive at the starter relay (12V to the 86 terminal while turning the key on "start", ground signal to 85, starter spinning by jumping 30 and 87).

It is just like a boad TDC sensor but I have no code at all.

WWDiesel · **Posted:** Fri Dec 09, 2016 10:31 am

sfcl wrote:

I did it already. And all current arrive at the starter relay (12V to the 86 terminal while turning the key on "start", ground signal to 85, starter spinning by jumping 30 and 87).

It is just like a boad TDC sensor but I have no code at all.

A bad CPS will not keep one from spinning over with the ign. switch!!!

sfcl · **Posted:** Fri Dec 09, 2016 10:36 am

Correct!

Do we agree that what could keep the starter motor to spin would be:
- Ignition switch (replaced)
- Clutch pedal position sensor (checked)
- Fried PCM

Is there something else which can avoid the starter motor to spin AND the engine to fire?

Ignition switch

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