trans problems : hunting gears ,hard shift,loss of power

[swhitney133]

Need some help on diagnostics of the E40D trans in my 1989 van with the 7.3L. I have been looking at posts and threads on this trans but the tach sensor I don't understand. The corrosion of connectors and tps settings I get. Any info on wiring harness of the trans for diagnostics

[OkieGringo]

The trans has gone into 'limp mode', usually because one of the 4 sensors that send info to the trans computer. Disconnect BOTH batt + cables for 1 minute. This will reset the computer. But most likely it will go back into 'limp mode' soon until you find the sensor that is malfunctioning. Does your tach on the instrument cluster jumping around while driving? Yes? Then replace it, about $50.00 ONLY available at the Ford 'Stealership'. Does the speedometer needle jump around, even the tinyest bit? Yes? Replace it, available at autoparts store for around $35.00, yours is the mechanical one and therefore ~ $10.00 cheaper than the newer electronic ones. If you have the 'tps'/FIPL set correct and it is ok, good, but they are available at autoparts store for < $20.00. The last one (MLPS-Manual Lever Position Sensor)is on the side of the trans where the shift lever enters the trans. It is available on the internet at Makco Distributing for $50.70 with shipping or at the 'Stealership' for $110.00 [img]/ubbthreads/images/graemlins/eek.gif[/img]. But, you'll also need a special gauge to install it correctly available on the internet at SPX Corp. for about $45.00 + shipping. There is also a relay on the drivers side fender, available at autoparts store for ~$17.00 [img]/ubbthreads/images/graemlins/shrug.gif[/img]. You asked for it. OkieGringo

[swhitney133]

I don't have a tach guage on instrument cluster. Is there a way to check my tach sensor for continuity or volt testing?

[Snotzalot]

Besides checking the settings of the TPS, you need to see if it is good all through it's range, put the VOM on the TPS and open it up slowly to see if any spots are "dead". Typically a bad MLPS throws the trans into neutral at the worse possible moment. I'd R&R the plug on the RH side of the trans first, then check the TPS. Quite ofetn the plug is bad on the RH side of the trans and replacements are available.

[swhitney133]

I cleaned up my connections on all sensors and rebooted the computer by disconnecting my negative cables for 2-5 minutes. Reset my tps voltage range with no dead spots from closed throttle to wide open throttle. My range seems to be a little higher than most. I think I set it at 1.2-4.3 which seemed a little high for the shifting so I lowered a bit by sight and it seems to be shifting right where I want it to but I didn't check the voltage range so I am probably right in there or damn close. The relay your talking about OkieGringo is on my passenger side I believe and I'll check into it. Thanks for the help