I have an 88 ranger 4x4 I just bought to putt around in. Anyway Im thinking, you know a 2.9l V6...gas sipper....WRONG gas guzzler. I think it has to do with my truck never going into 4th gear. Ill be driving around and it goes into 2, and 3rd no problem. But the truck RARELY goes into 4th. And let me tell you, cruising down the highway at 75 while pushin 4,000 rpm isnt fun and sure wastes gas. Anyone else have this problem in their tranny? Its a pure beater but I need it to get to work for a while but going 70 miles and using 9 gallons of gas sure sucks.

 

I think the earlier A4LD uses a pressure based overdrive switch. if the switch fails or is incorrectly calibrated it will not trigger. If the line pressure is low, you will have problems too. I would look into that. The problem is much of this would require testing procedures and equipment that ate not handy to the DIY or to most small shops. A transmission shop could take a look at it and see what is going on.

 

As I remember '88 A4LD had one solenoid only - OD solenoid, but TC lock up was hydraulically controlled. There are 2 wires on solenoid RED - ign on (kl.15 in EU wiring diagrams) and Tan. LT blue (this wire runs to #52 pin on PCM. Switch inside PCM shorts this wire to ground and OD actuated. Broken circuit cause code (89 ore 98, I dont remeber) but not actuate CEL. Well, just unplug PCM connector and measure pins #54-52 resistance. As I remeber something about 20-40 Ohm. If it is OKay plug connector back and carefully split #54 wire (Tan. LT blue) and measure voltage on it with ign. on. If no 12V - check voltage on solenoid red wire (may be broken). If 12V ore from 10 to 14 try carefully short this wire to ground - wire running to SOLENOID, NOT PCM (you may hear click and see spark). It means that wire and solenoid are OKay. To be sure no internall tranny problem, run this wire to cabine and install override switch and try to shift into OD when you drive at 3rd "manually". If it works, no reason to check tranny. Well, then try to add LED to see that PCM actuates OD. If not do not blame PCM and take it apart to change switch. you may have failed VSS and PCM knows nothing about truck speed.