Muddz

The 95 ZJ 4.0L was starting and running fine then a couple of times there was no ignition, tired in both park and neutral and nothing.

The last time it happened a person was going to tow me and I tried one last time tuning the key from acc to start and the engine started right up.

after several days I went to start the ZJ at home and again nothing, tried to toggle from acc to start and still nothing. I thought the problem might be the NSS switch so ordered a new one, today it arrived and after installing there's still no ignition. No sound from the starter or starter solenoid. The dash/inst. lights come on as usual.

I suppose I can look at the wiring to the starter. I don't think the problem is with the starter relay as I swapped in another relay. The ASD relay I still need to check out.

Possibly the problem is the CPS? On my XJ 4.Ol if the PCM doesn't see a signal from the CPS the PCM uses the ASD relay to prevent the engine from starting.

I do have another ignition module ignition key and cylinder.

Perhaps I should test the CPS or just order a new one? I'm uncertain if it's a one or two bolt mount.

Also the ZJ NSS switch that uses three pins. Does the nss plug fit onto the NSS in either direction?

IIRC the three pins on the NSS is (1) Backup lights (2) PCM (3) Run/Start

So the PCM (2) would always be in the middle and the position of (1) and (3) doesn't matter?

The nss and nss plug aren't keyed so I assumed it was either direction.

dave1123

The CPS doesn't keep the engine from cranking, only keeps the fuel pump, ignition and fuel injectors from turning on if there's no signal. Those are the 3 things the PCM controls via the ASD and fuel pump relays.

Muddz

By "it' I meant "it" the PCM uses the ASD to prevent the engine from starting. (if bad signals from the CPS) The PCM in my XJ does shut the engine off if it gets incorrect signals from the CPS, using the ASD relay. I had this happen one time while traveling in heavy sand a few feet from the ocean shore. A bad CPS reacted to additional heat created by heavy sand and sent bad signals to the PCM which then used the ASD realy to shout the engine down, while only a few feet from the ocean with the tide coming in. So I waited a half hour or so hoping not be washed out into the sea, long enough for the CPS to cool down again so it could send good signals to the PCM. The CPS cooled down in time not to get washed away into the ocean.

On my 98 it's been a while so my memory isn't all that good but seem to remember the ASD is directly connected to the starter relay. The PCM controls the starter relay through the ASD relay which supplies power to the starter relay.

I can't remember off-hand which other relays the ASD relay powers at least on my 98 XJ.

I'd have to go back and look at the service manual an schematics. Approx. 10 years ago I fixed all the electrical problems with my 98 XJ at the time I was pretty much up on everything reading through manuals, schematics, etc. However it's been nearly 10 years since I've had any electrical issues with the XJ. and recently purchased the ZJ which the previous owner mentioned he had some engine ignition problems. (turning key and nothing happened) He said after he installed a new battery and the ZJ started to start normally again. He thought replacing the batter had reset something. Perhaps from the security system or other.

This ZJ Limited does have an optional Passive Security System with an "engine no run" feature. But it's not an ignition immobilizer and is suppose to work by setting off an alarm and preventing ignition. if someone tampers with one of the monitored switches. I'm not certain exactly how the "engine no run" feature actually works i.e. if it actually disables the ignition, etc.

Passive Security system monitors Hood ajar switch, door ajar switch, lift-gate key cylinder switch, lift-gate ajar switch, * ignition switch, power doors lock and unlock switches, door key cylinder switch, RKE Arm, RKE Disarm (95 only)

The passive security system has it's own module with relays, etc. that I believe is part of the CCD bus and communicates with the PCM.

Might have nothing to do with engine starting and ignition. From what I know it's capable of preventing the engine from running.

dave1123

I was under the impression that the CCD data bus system began with the 99 Grand Cherokee models. I do know that my 2000 WJ has this system and everything is monitored by the body control module. All the door latches and the SKIM are part of the security system as well as the RKE receiver. I know for a fact that the hood doesn't have any switches on it because you can lock the jeep up with the alarm set and the hood on the safety catch.

Muddz

My 95 ZJ has what they call a Passive Security System and does have a monitored hood switch. Normally when you secure the vehicle with the power door locks an indicator lamp "Security" flashed from the inst. panel for 15 seconds and the pass. sec will be activated. If the hood is already opened the "Security" light won't flash and after 15 seconds the security system will still activate.

So the hood at least on my 95 doesn't need to be closed to arm the passive security system. On my Passive Security System there is a diagnostic mode which can be activated using a DRB scan tool and also without a DRB scan tool by switching the ign. key three times to accessories will put the pass. sec. system in a diag mode. To take it out of diag mode turn the Key to Run which you should here the horn honk once indicating the ign. is being monitored ok, after the horn honk the pass. sec. will be out of diag mode.

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1999 WJ I believe uses a PCI bus not the CCD bus. My 98 XJ and many earlier use a CCD bus. CCD was first introduced by Chrysler in a 1988 Dodge Dynasty. Most likely was used in ZJ's in 1993 as well as XJ and YJ (Wrangler) . For the XJ I don't know. Chrylser took over Jeep in 1987 and came out with the CJ-7 replacing the AMC/Renault Wranger. Early Cherokees are Renix and have Renix PCM's. Grand Cherokee in 93 - 95 (some early 96) used OBD1 which was actually created by CARB but eventually adopted by the Feds when they developed and created OBD2.

RENIX = 1984-1990 w/AMC engine (150ci I4 or 242ci I6. Not the 173ci V6 or 126ci turbocharged Diesel.)
OBD-I = 1991-1995 w/150ci I4 or 242ci I6, 1984-1986 w/173ci V6
OBD-II = 1996-2001 w/150ci I4 or 242ci I6.

• Chrysler communication protocols

1. CCD ( Chrysler Collision Detection, 7812.5 Bps )
2. PCI ( Programmable Controller Interfacer : SAE J1850 VPW, 10.4 KBps )
3. SCI ( Serial Communications Interface : J2610, 62.5 KBps )
4. ISO9141 ( 10.4 KBps )

Chrysler PCI Bus ( SAE J1850 VPW )

Introduced in 1998, replaced CCD as a Body Protocol. A vehicle will have either CCD or PCI, not both and PCI is a Single Wire Network. PCI Bus Speed 10.4 kbps and can support up to 32 modules or nodes. It is used as a global OBD-II scan tool interface.

Muddz

I tested pulled and tested the starter and solenoid and the starter runs ok.

Also connected a DMM to pin 86 of the starter relay socket and battery gnd. Turned key to start and am getting 12 volts to pin 86.

Muddz

I tried another known working starter relay from an XJ and the ZJ started, however when I tried to start a second time nothing.

Listing more carefully while turning the ign. key to start (non start condition) I can here a clicking sound under the dash some where near the middle or just to the right of the middle of the dash.

I'm able to engage the starter by jumping pin 30 (hot) to pin 87 (solenoid)

97grand4.0

Check the socket where the relay plugs in. Saw a video yesterday of a guy taking apart a malibu fuse and relay block to find burnt connections to the pins for the fuel pump relay. The relay needs to plug in nice and tight you look in where it plugs and should not see through to the other side, the contact should not be bent aside. Then look at the wire to the contact, if it's discolored on the insulation, if the wire is greenish, its likely heated up and burnt. I suppose you could use an ohm meter to do the same thing.

Muddz

Installed the new starter with lifetime warranty and the ZJ now starts ok. The old solenoid works intermittently and makes no clicking sound. I'll need to dismantle the old starter to determine if it can be rebuilt.