Hey all,
I've got a 97 that won't start once the ignition has been turned off after it's been running for about 20ish minutes around 90 km/h.
When I do turn over the key I get only my dash lights. No crank, nothing. There is a clicking coming from the inside fuse/relay box and I can hear my fuel pump run.
I've replaced the starter to no avail as well as ripping apart, cleaning and reinstalling my neutral safety switch. It'll start in park and neutral, reverse lights work.
It started out around September and I'd have to wait maybe 5-10 minutes but now I'm up around the 1 hour mark, pretty sure it has been getting worse with time and not colder weather as even on warmer days (5 celcius vs -15) I still have to wait around an hour for the Jeep to start, but I'm not 100%.
I've checked around on multiple forums and there have been a few people with similar issues (https://www.cherokeeforum.com/f2/199...hen-hot-74205/) but nothing exact enough to help me locate the problem.
This one has me boggled and is driving me nuts as it's my daily driver.
Thanks in advance.

 

You have a problem with the "starting circuit". So this is not a crank sensor issue as was mentioned (by me) in that other thread; that sensor has nothing to do with the starting circuit.

Spend some time snooping around inside of the PDC, the power distribution center under the hood that holds critical relays and fuses. You are suffering a thermal (heat related) failure somewhere.

I would start by swapping the STARTER RELAY in the PDC with another non critical relay. The relays inside the PDC are all of the same part number, so swapping is not a problem.

 

Ok, relays are switched around, I'll give that a try. I figured it wasn't my cps as the Jeep isn't even trying to crank at all.
I swung into my local auto shop to price out a new relay and brought mine in with me for reference. The mechanic told me chances are it isn't the relay as mine looked fine and it takes a bit to make them blow. I'll take his word on that for now.
My next step to check if it's not the relay is the actual wiring going to the starter to see if its providing enough current, perhaps it's not grounded properly or the wiring is corroded, I seem to recall that being a common issue with older Jeeps?

 

Yes, you could have a wiring problem.

See if it happens again after relay swapping and if it does, inspect every inch of wiring and refreshing grounds is NEVER a bad idea!
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

 

Have you looked at the connections to the battery? I had the same issue and found corrosion on the terminals. Replaced the terminals and all is good.

 

It may also be the battery terminal post on the starter. Good thing to look at anyway. Had to clean the battery terminals on mine when I bought it, with one of those terminal cleaners that have inside & outside wire brushes. I never liked top-post batteries anyway. It's 1920s technology. I never have problems with side post terminals...
There's been a couple threads here talking about the battery ground cable where it's bolted to the engine block. That may be worth cleaning up also...

 

It wasn't the relay unfortunately.
I'll start checking wiring. The posts looked ok when I had my terminals off to put the new starter in but I'll check them again along with the posts on the starter as well.

 

Don't overlook an overheating ignition switch either. The start function might only work when it's cooled off. Check the plug for discoloration and/or melted spots.

 

A bit of di-electric grease on the clean connections will help prevent future corrosion.

 

Hey all,
Thanks for the info. I'm a bit swamped these next few days with work as we finish off before Christmas holidays but hopefully early next week I'll be able to dig a little deeper into this.
Cheers

 

Interesting... TJ's mention of a "starting circuit" is... Interesting.

1995 Jeep Grand Cherokee Laredo - 4.0 - 4x4

A feeble Mechanic Tampered with my Jeep. When General Maintenance was requested, oil change, tune up (spark plugs, wires, rotor & cap), the bizarro decided it was a good idea to cover my engine with Degreaser & I assume he rinsed the engine off with water, after coating it with Degreaser, because his story never mentions it. Again, I assume. I can still identify remnants of the Chemicals, as the Air Box, Intake Hose & other components have 'spotty' residue.

Anyway, after (supposedly) changing the plugs, wires, cleaning distributor cap contacts (he did not replace cap or rotor), he apparently "Cleaned & Degreased the engine", which gifted me with a Check Engine Light, that appeared because he somehow shorted out the TPS. How he effected the TPS, is again, assumed that was the Effect of his Cause of "Cleaned & Degreased the engine".

Since then I've had a plethora starting & idle issues. Initially, my cranking time was longer, but with our first day of Cold weather 10/31, I've been contending with an intermittent starting issue. The oddity is, its not consistent, only happening on days the temperature is (approx) 36-40 degrees & below. The Colder the Temp, the longer it takes for the PDC Relays to respond & tell the Fuel Pump to do its thing.

I've done Fuel Pump Pressure Test (good) & Tested my Battery (good) & checked / clean Grounds at the battery (good) & I've switched the Relay's around (no change) & 3 weeks after that, discouraged as I am, needlessly bought 2 new Relays the other day & switched out the ASD & Fuel Pump Relays & got the result I knew it'd have = no change.

After weeks of trouble shooting the start, I've learned it isn't about cycling the key multiple times, its more about Turning the Key On & waiting. Wait until I hear the Relays click & Fuel Pump prime simultaneously. Then Crank the engine it starts.

Oddly, Temperature approx 40 degrees & above, it starts regular (turn key, instant relay & fuel pump action & vehicle starts).

I don't know what the deal is. The feeble mechanic could of compromised the spark plugs or... a long list of things he could of done to sabotage the Jeep, but mainly, haplessly spraying the Degreaser & assumed soaking the engine with water, who knows what damage he caused. Degreaser, a corrosive chemical, right?

Chemicals, water or any other liquid, not good for electronics, such as PDC, PCM, IAC, TPS, the Dizzy, Etc., and if treating an engine (cleaning), all these items should be carefully covered & protected. The way the guy thinks & operates & the fact he shorted out the TPS, I guarantee he covered/ protected nothing!
[he doesn't really think & he operates recklessly - he's caused me a lot of grief, stress & money]

I started a thread about this, but I think viewers just think I'm long winded.

Anything more about this "starting circuit", plus any thoughts if its possibly related to what I've described above?

Also, should I (we) be hearing the Relays @ PDC ? I hear them loud n clear, through my Air Vent, located @ the Glove box. I cannot recall if I heard them as loud as they are, prior to the Feeble mechanic tampering with my Jeep in September. When I hear the clicking, the Fuel Pump kicks on, right behind it. I hear that loud n clear too.

Thanks - Advice, Suggestions, Miracle Fixes, are Much Appreciated!

 

Brew, the "start circuit" TJ was referring to is the circuit that operates the starter motor.
Basically the ignition key supplies +12v to a "start" relay in the PDC.
The other end of that relay's coil is grounded through the NSS. When the start relay operates it feeds +12v to the starter solenoid, which in turn operates the starter motor.
The other necessities, fuel pump, ignition, are switched on/off by the PCM, some through the ASD (auto shut down) relay in the PDC.

I think you have water in a connector somewhere. Take EVERY connector under the hood apart, blow it dry, reassemble. And no, the TPS does not like water at all.

 

Hey Brew,
Can't say that our problems are identical, I'm not sure if mine is affected by the weather, although today I ran into work to grab some paperwork and it ended up taking 2 hours before my jeep would start from the time I turned it off, but there was a good wind chill. I can't say that I've heard my relays in the PDC audibly click but then again I haven't been listening for them, but I do hear a clicking from my fuse panel inside the vehicle when I turn the ignition over. I'll have to try turning the key on and leaving it, usually I just cycle the key in bouts of frustration between cigarettes while I wait.
I honestly can't tell you what the previous owner of my Jeep did to it as far as maybe spraying the engine out with God only knows what. I paid $800 for mine and dropped maybe $400 into it to make it road legal between tires and mostly front end work, so honestly I can't really complain. However, that being said, my rear wiper doesn't work (switch is kaput and there is no washer fluid line coming out of the trunk lid), I have speakers in my air vents, my a/c is kaput and I only get hot air through my window defroster, my horn doesn't work although I do hear a clicking coming from my fuse panel in the kick plate, my power mirrors don't work, my cruise control works but the light doesn't come up in my dash, my gas gauge isn't reading accurately, and my oil pressure fluctuates once the engine is hot.
Most of those are an easy fix or something I'm not overly concerned with but there seems to be a large amount of electrical issues that makes me wonder what the previous owner did (or didn't do) to the vehicle.
I haven't had much desire to trouble shoot my starting issue as I've been working a ridiculous amount and we just got about a foot of snow dumped on us.
Come Monday though I'm taking it over to a buddy's garage to take a stab at it. Planning on replacing most of my wiring coming from my battery and cleaning up all my connections and grounds, copious amounts of dielectric grease will be used.
Anyways, onward and upward, I'll update on Monday once (if) I find the issue.

 

Hey Radi,

Thanks for the Sound suggestion(s). I responded & gave you props @ the following thread link.

https://www.cherokeeforum.com/f5/int...erokee-203096/

Viewers will also find the next link there, but I'll place it here too, speaking about & detailing Bad PCM Capacitors.

Link directs to page (3), because of posters detailed description of their odd, often Cold weather effected Starting issue(s).

http://www.jeepforum.com/forum/f13/f...51/index3.html

 

Hey L4yer,

If you're unsure if the PDC Relays are *clicking (like I've described mine are doing, loud n clear), then I'd suggest... Just as curiosity, to the least... well, let's see... I don't know where your PDC is located, but on 95' Grand Cherokee, I can open the hood & at the left corner, toward the Hood Spring, is the PDC. If yours is similar, you can open the Hood, and then from the *Passengers side, Reach-in & turn the Key into the On/ Run position & keep your ear focused toward the engine compartment.

As long as the key @ On/ Run, just wait & listen for how long it takes the Relays to sound off... If they sound off (like mine are doing). If more than a few minutes pass & you heard nothing, then patiently *cycle the key - All the way Off, then back to On/ Run & listen again. With my deal, I'm also waiting to hear the Fuel Pump cycle, which has reliably happened as soon as the Relays *click

With my Cold weather effected Starting Issue, If I try to *crank the engine anytime prior to hearing the Relays & Fuel Pump, then I'm just prolonging my start time - it actually makes it worse. A lot of Trouble Shooting / Trial & Error to reach this 'work around'.

[The engine would just crank & crank, seeming like its not getting spark or fuel, until a. it finally starts (rough) or b. the battery dies (it happened once & came close numerous times) The day the battery died, it took 3 hours of trouble shooting (doing all the wrong things) before I got it started]

All in All, I've no idea if anything I'm writing relates to your deal, but its up to you to rule out what is, or what isn't. You can view the trail I'm on now, by following the links I left replying to Radi. It may or may not pertain to you, but I'd suggest thoroughly reading the PCM Capacitor thread.

Anyway, keep this updated so those of us interested can be informed. Thanks & Take Care.