Why does my gladiator jerk forward when starting

[JTinVA]

My jeep seems to jerk forward when I start it. Anyone else notice this

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[Kevin_D]

Which transmission?

Kevin

 

[JTinVA]

Which transmission?

Kevin

It’s the automatic

 

[ShadowsPapa]

My jeep seems to jerk forward when I start it. Anyone else notice this

How about some details -
Gas or diesel?
Manual or automatic transmission?

 

[kevman65]

Are you parked on an incline or a decline?

Do you set the parking brake when you park?

Is your shift lever FULLY engaged in P?

Take it to a dealer, let them diagnose. That is potentially a dangerous situation.

 

[JTinVA]

How about some details -
Gas or diesel?
Manual or automatic transmission?

Gas and it’s auto

 

[ShadowsPapa]

LOL - ok, we crossed messages..............
Gas automatic.
You have to have your foot on the brake to start it - you are saying it jerks forward against brakes?

In any case, I agree with kevman -

 

[JTinVA]

I guess it’s more of a buck forward. Its definitely movement tho.

 

[JTinVA]

Are you parked on an incline or a decline?

Do you set the parking brake when you park?

Is your shift lever FULLY engaged in P?

Take it to a dealer, let them diagnose. That is potentially a dangerous situation.

No incline and it’s fully in park. No I don’t set parking brake

 

[DailyMoparGuy]

Like Kev and Papa said, I’d take it to the dealer as soon as possible (assuming you’re under warranty). Hold brakes, hit start button, then it surges forward?…that doesn’t sound good at all.

I’d bring video proof to avoid the whole “wE CoULdN’T rePliCAte THe iSsUe” BS that the incompetent dealer techs tell customers after holding their vehicles for 4 days.

 

[kevman65]

You may think you're parked on flat, level ground. But if the JT rolls forward or rearward after you put it in park, then the parking pawl is not fully engaged.

Then when you start the JT it can lurch until it hits the parking pawl.

The parking pawl is actually the weakest link in the whole safety part of starting an automatic transmission and they can and will fail.

I was taught eons ago, come to a complete stop, with vehicle still in gear apply parking brake, then put vehicle in P. This locks everything in place for when you start, plus if the pawl does break, the vehicle will still be there when you get back.

 

[HenrytheDestroyer]

Going to go on a limb and guess you’re not keeping your foot on the break during the entire start up process. Likely something with the park/drive transmission shift.

Might be something not good, still.

 

[ShadowsPapa]

You may think you're parked on flat, level ground. But if the JT rolls forward or rearward after you put it in park, then the parking pawl is not fully engaged.

Then when you start the JT it can lurch until it hits the parking pawl.

The parking pawl is actually the weakest link in the whole safety part of starting an automatic transmission and they can and will fail.

I was taught eons ago, come to a complete stop, with vehicle still in gear apply parking brake, then put vehicle in P. This locks everything in place for when you start, plus if the pawl does break, the vehicle will still be there when you get back.

But to not engage every time?
I can see once in a while, especially if the driver is the sort that touches the brake only long enough for it to crank, then lets off, but the odds of park failing to engage every time is pretty slim. There's nothing to make it want to move other than the viscous action of fluid between the shafts in old-skool transmissions, likely eve less in these. No clutch packs, no bands, engaged to make it want to move.
I am wondering about a true fault with the transmission.

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