manual transmissions only engaging in number 4th gear

Even manual transmissions have a “limp home” mode. “Limp Home” mode, as the name implies, allows you to get your Transit home — as you did — or to a service area for work. That would have been my first piece of advice. You do have to get your van to a service area as soon as ou can because you are making one gear essentially handle the work of an entire transmission.

“Limp Home” mode usually kicks in when something fails. In the case of your Transit, it could be something like a misadjusted shift cable or a troublesome neutral-start switch. The cable may be binding in its runner. Because it may be binding, the cable is unable to engage each gear so the transmission control module (TCM), the computer that controls your van’s manual transmission — yes, manual transmission-equpiped vehicles have them as do automatics — isn’t seeing each gear and as a result the tranny has gone into “Limp Home.”

The same is true of the neutral-start switch. Attached and activated by depresseing the clutch, the neutral-start is a safety device. Unless you fully depress the clutch, your van won’t start, so it won’t lurch ahead when you twist the key to start. Once you push the clutch down, your ignition key will engage and the starter will turn the engine over.

If the neutral-start is failing, your Transit will go into “failover” (another name for “Limp Home”) and it will engage your transmission in one gear so that you have the ability to move the Transit to a service area.

The two possibilities I have just outlined are quick thoughts off the top of my head. There are any number of issues that could have caused “Limp Home” mode to be initiated.

My suggestion is this: get the Transit to a dealer’s service shop as they have the latest factory-backed and generated diagnostic software. Once your Transit is in the service line, ask to have a full diagnostic workup performed. This is don’e with an OBD-II scanner. The scanner polls all systems, including the engine control module (ECM), to see what error codes may have been sent to memory. I suspect you will find several codes in the readout. Take that information and have the services indicated performed. I believe you will have your tranmission working again in no time.

You may wonder how much this could cost, which is a good question. If it is just a binding cable, then you are likely looking at about two hours’ time which is a little under $300. If it is the neutral-start, then you are looking at about four hours, or about $600 (in the USA). Other systems will, of course, cost more. I don’t think, though, that it will cost you any more than $1,875.