koda2000
Explorer Addict
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- September 2, 2011
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Since I bought my 2001 Sport Trac 5 years ago I've been having an annoying issue with my automatic transmission. Although the previous owner pretty much destroyed this truck, through lack of maintenance and abuse, the transmission has always worked perfectly in the forward gears. The only issue I've had with the transmission has been that if reversing up a steep grade the transmission will slip and shutter something awful. On a relatively flat surface, or slight grade, it will reverse with no issues.
I've asked the forum about this issue in the past and the only reasonable answer I got was that the EPC solenoid wasn't applying enough pressure to the reverse band. I had it in mind to investigate replacing the EPC solenoid at some point, but I wanted make sure this would fix my issue before firing the parts cannon.
Because this vehicle has had bigger problems, which I just solved by rebuilding the engine and replacing both cylinder heads, I wasn't too concerned about the slipping in reverse issue. Now that the engine is finally running great I'm turning my attention to the transmission issue.
Restarting my internet searches for what might be the cause of my reverse slippage informed me that yes, it could likely be related to my EPC solenoid, but the research also warned about the roll of the TCC solenoid and other transmission fluid pressure issues. Reading the list of symptoms of an EPC solenoid problem nothing exactly fit the problem I was experiencing. Then I stumbled across the thread below, which fit my symptoms to a "T"...
www.explorerforum.com
I'm thrilled to have found this thread and hoping that this is my issue (a bad contact in my MLPS - Manual Lever Position Switch, aka the neutral safety switch, aka the range selector switch). This switch is responsible for telling the PCM when the transmission is electronically in reverse and that the line pressure should be increased to the EPC solenoid. If this doesn't happen the PCM thinks the transmission is electronically in neutral and insufficient pressure is applied to the reverse band, which will cause the reverse bad to slip when stressed.
I never would have suspected the MLPS could have been my problem w/out having found the above mentioned thread. I plan to now check the adjustment on my MLPS to make sure it's properly adjusted to its neutral center-line mark and if necessary I'll remove the MLPS switch, take apart to check its internal electrical contacts. If this turns out to be my issue even a new Motorcraft MLPS is under $50 on RA (there are less expensive versions available) is easily replaced and I don't have to even drop the trans pan to replace it. And to think I was considering pulling my transmission and having it rebuild... Finger's crossed that I find a misaligned or bad MLPS.
I've asked the forum about this issue in the past and the only reasonable answer I got was that the EPC solenoid wasn't applying enough pressure to the reverse band. I had it in mind to investigate replacing the EPC solenoid at some point, but I wanted make sure this would fix my issue before firing the parts cannon.
Because this vehicle has had bigger problems, which I just solved by rebuilding the engine and replacing both cylinder heads, I wasn't too concerned about the slipping in reverse issue. Now that the engine is finally running great I'm turning my attention to the transmission issue.
Restarting my internet searches for what might be the cause of my reverse slippage informed me that yes, it could likely be related to my EPC solenoid, but the research also warned about the roll of the TCC solenoid and other transmission fluid pressure issues. Reading the list of symptoms of an EPC solenoid problem nothing exactly fit the problem I was experiencing. Then I stumbled across the thread below, which fit my symptoms to a "T"...
Solved - 4R55E shudders & slips in reverse. All of the other gears are fine.
Hello all. First of all I did check thru the forum looking for a similar problem but none exactly as mine. This is for a 1996 Explorer XLT, V6 4.0 ohv, 2wd, 4R55E trans. Trans overhauled 2 years ago (all clutches & bands changed) & ran fine but recently began shuddering & slipping in reverse...
I'm thrilled to have found this thread and hoping that this is my issue (a bad contact in my MLPS - Manual Lever Position Switch, aka the neutral safety switch, aka the range selector switch). This switch is responsible for telling the PCM when the transmission is electronically in reverse and that the line pressure should be increased to the EPC solenoid. If this doesn't happen the PCM thinks the transmission is electronically in neutral and insufficient pressure is applied to the reverse band, which will cause the reverse bad to slip when stressed.
I never would have suspected the MLPS could have been my problem w/out having found the above mentioned thread. I plan to now check the adjustment on my MLPS to make sure it's properly adjusted to its neutral center-line mark and if necessary I'll remove the MLPS switch, take apart to check its internal electrical contacts. If this turns out to be my issue even a new Motorcraft MLPS is under $50 on RA (there are less expensive versions available) is easily replaced and I don't have to even drop the trans pan to replace it. And to think I was considering pulling my transmission and having it rebuild... Finger's crossed that I find a misaligned or bad MLPS.
