*** Note: speedo works, cruise works fine, o/d switch lights up, voltage regulator in pcm crapped out so now externally regulated ( was working prior to external regulator ) only pulling code 41. If this helps eliminate some parts that would control it. If the cruise works, tps would be rules out i would assume? only thing i can think is grounding out the ground to the trans to a switch? ***

I got a 92 b250 conversion and the voltage was all over the place. I bypassed the voltage regulator in the pcm with just an external and now the voltage works great.

However, I am having problems now, Overdrive doesn't engage. Switch lights up cool but nothing. I have a nearly 24hr trip coming up and well, frankly would like to fix it without spending a lot of money. Is there a way that i could just hook up the overdrive to a switch or anything so i can just turn it on and off? also, before i go, would there be any things i should check to see if is bad ( other than connections, but im more leaning toward the pcm being bad cuz the voltage reg went, sooo... ) is a switch possible?

 

I would not attempt a 24 hour drive without overdrive, unless I was towing something, and driving only 55.

Do the Key dance, check for codes stored in the computer.

On my '89, if the Vehicle Speed sensor is not working( code 15) the overdrive will not work.

I think on a 92, if the VSS is not working, the speedo and cruise will not work, but am not sure.

 

last time i pulled codes is when the regulator was going bad. Had 46(charge voltage low), 51( lean ), and 12 (battery disconnect). Speedo works, odometer doesnt but that would just be gears in the cluster.

anyhow, the trip is required and i need to get it fixed, regardless. I was reading about people using those potentiometer things, which may work, but since those have 3 wires, would that be similar to any grounded switch? 2 powers and a neutral? just something to turn in on and off...

Ill try the codes again but im just looking for a way to rig it so it will work without replacing anything to oem standards.

 

well, the only code i get now is code 41 ( generator fields not switching properly ) or some **** like that. probably caused by my rigging up of the voltage regulator i would assume.

 

I do not know how to put a manually operated switch to the overdrive and lockup. Wish I did.

There can also be issues with the tranny itself. Check the fluid level and condition with the engine idling in neutral. I hear OD is always the first to go.

Use ATF +4 only and if you had some shop or quickie lube joint do a tranny pan drop or flush you can be 98% sure they did not use ATF+4.

Wish I could help. If you do figure out a way to manually switch it, please post how.

 

fluids were the first thing i checked. all good, not burns or anything. I always add a little lucas because its been a miracle worker in demo trans.

it used to act odd when driving, it would want to shift into od for a while just sitting in 3rd then if i fuzzled with the gas or just let it go, it would go, now it doesn't do that.

What i was reading that is the option of putting the ground wire off the trans to a switch thus allowing manual control because all the tps does is ground out?

im not sure of actual location of the tps on this van, my assumption is that its in the pcm, along with 90% of the other bs that fails.

 

The throttle position sensor is on the throttle body. It is turned by the same mechanism that opens the butterflys in the TB, activated by the throttle cable.

An ECM/PCM rebuilder, Cardone claims that it extremely rare for one to fail on it's own. Something causes them to fail. The biggest culprit according to them is the overdrive or lock up solenoids in the transmission. If you Google cardone and search their site you will find this claim.

I have replaced my '89 ECM. Before I did so, I wasted a lot of money and time replacing sensors. I had cleaned every single connector, unravelled every single wiring harness, and cleaned and inspected 90% of the wiring in my Van.

I found that some wires leading to the transmission were burnt and had been grounding out on the tranny bell housing.

You might just want to disconnect the battery, and remove, clean and inspect the connectors at the ECM. Look for wires that have been poked with a DVM probe or test light.

Also I believe the ground for the ECM attaches at the base of the Coil. Make that one shine.

 

well i will check all those connections, looks like on the top of the trans some of those wires look sketchy. now my question is do the 3 wires from the tps run directly to the trans or does it go to the pcm then out? im just trying to find some way to just kick that o/d on... if the wires go direct, in theory i could just run a 3line switch direct in place of the tps?

 

i had a moment there lol, it must junction somewhere to power the o/d... im so confused with vehicle electrical