after transmission swap, my car still broken - Benzworld.org

feras · 06-28-2008, 11:32 AM

hi , first time for me here and it is a great fourm..my car is s420 1993 with 4 speed transmission, i had to swap transmission after water mixed with oil, when i got the car back it was ok all shifts smooth. i stopped on trafic light and started to move and my problem started. the car started with first gear then after a delay shifted to third gear. there was no second gear. and it shifts to the fourth gear when reach 3500 rpm. i know the car should start with second gear not first, when i leave the car to cool down and start driving it drives normal. but if i stoped or reverse the problem comes back. so i went back to the garage and told them about the problem. they removed the gearbox and install another one... a total gearbox with all parts attached to it ..... took the car back and after 15 min the problem came back again.... i think there is something out side the gear box cousing the problem so any body got a vacuum digram or electric digram for the gearbox can help me... i payed alot of money for the swap and the garage couldn't find any thing wrong... thanks alot

feras · 06-29-2008, 10:26 AM

by the way the new gearbox been taken from s500 and my car is s420 is ganna be a problem or they are the same... plz any one got an idea? iam thinking about the first gear valve but i don't know the location for it .. i need a digram ....

**bayhas** · 06-29-2008, 11:48 AM

you need to put in the correct tranny for the S420 so the tranny would shift at the correct torque point and not too late/too early

what happened is you drove the car for a while with the "closed loop" variables stored in the tranny PCM, after a while of driving with the new tranny, the PCM is trying to filled up the variable table and trying to run the tranny as S420 tranny (722.323 if i remember correctly) little does that PCM know that its controlling a 722.325... when the PCM realizes that the output of the tranny does not comply with its input (torque, acceleration, and shift points) it assusmes that something is broken and goes in a "safe mode" called transmission protection mode

to see if my theory is right, try to disconnect the battery ground cable over night, and see if that solves the problem for a while again... you probably need to reset "safe mode operation" in the tranny PCM with a scanner

jhodg5ck · 06-30-2008, 06:13 AM

These early .3's have very little in the way of electronic controls.. Were this a .6 I'd think the controller issue a more likely culprit.

Jonathan

feras · 06-30-2008, 05:10 PM

ok... i understand your theory... but the transmission is controled by vaccum and oil prussure.. there is no computer controling the transmission as far as i know.. so how can the tranny go to safe mode?? there is two vaccum hoses connected in the right hand side of the gearbox and one kickdown cable... on the other side there is three plugs...one for over load.... one for the ignition switch and the third one unknown for me...can any budy tell me which plug could disconnect the safe mode if the theory was right???

**bayhas** · 06-30-2008, 09:20 PM

the battery, to reset all of the modules.

and yes, there is a ECM dedicated for the tranny in the coffin box under the hood, and that is for all models, when activating the safe mode, it lowers the system pressure, to ease on the tranny, causing the shift points to be delayed and the o-x acceleration to start in the wrong gear.

jhodg5ck · 06-30-2008, 10:04 PM

I'm just curious as to how it's going to drop the shift pressure... I don't believe the modulator is under electronic control.

Jonathan

**bayhas** · 07-01-2008, 08:17 AM

the vacuum is...

fray · 07-01-2008, 11:46 AM

Does a .362 have an ECM too? When scanning the EGS, EAG module with a DAS STAR scanner it shows: not installed or not communicating with this module, msg. It comes back with the same msg when a feature is actually not installed as ASD for a 93 S600 car, but is the transmission ECM mandatory? and thus a different msg from the DAS? Thanks for your help. Yes my car is in transmission "Safe" mode. Everything in the engine side reports no errors...

Fray

feras · 07-02-2008, 04:53 PM

ok... i disconnect all vaccum hoses from the tranny,over load switch and the ignition switch plug.... the gearbox still act the same...first thing in the morning it works very normaly... after 15 min the problem starts again....it starts with first gear then jump to third with delay in all gears...when i move the selector to 2, it goes to first gear. the car got no ASR system... can any budy confirm this problem is a safe mode tranny? and which plug delver the safe mode signal to the tranny if the theory is right? iam sure that nothing to do with vaccum because i disconnect all hoses and lost the E/S selection an B selection and the tranny still act the same .