I was pulling my buddies '78 Bronco home from Michigan last week it was hot, out about 93°. Pulling fine for 250 miles at about 70 mph. Stopped to get drinks, and idled for about 10 minutes. Then hit stop and go traffic and cruised at 55 mph for a while. I noticed that when the traffic cleared up and I would try to creep back up to 70 mph the excursion was reaching 2100rpm and only going about 63mph. Previously it was running 70 mph at 2100rpm just fine all the way up to michigan. OD was working and I could turn OD off and it would shift out of OD and back in when activated. It just felt a little mushy. No engine lights not other signs of trouble. I do not have a trans temp gauge, just the idiot gauge on the dash, which of course tells nothing useful after warmup. Continued to ease it around 465 in Indianpolis onto 65 south. It was taking more and more power to maintain speed and climb ramps etc. We stopped to check out some things and trans fluid level was ok, color was ok. We turned the excursion off and started it again, and then we had check engine light on. We contined the 40 mile drive home and unloaded. The truck felt like it would go into OD but the TC would not lock up.
A day or two later pulled the codes and got P1744 and P1743. I also had a blinking OD off button light. I cleared the codes and they have come back already. It shifts ok, maybe a little rough 3-4 shift. OD seems to work ok, i have not taken it back on to interstate and I have not hauled a trailer or anything since I got back.
SO i have done some searches and I can see there was a TSB for the shift solenoid and that there is a new part number. THis is from the dieselstop Flashing OD Light. Solenoid Problems? - Diesel Forum - TheDieselStop.com
I have found P/N F81Z-7G391-CB online at tousley and others for a little under $300.
Has anyone pulled these same codes or had problems with lockup? What did you do to fix it?
History: I bought this 2002 Excursion in Dec 09 with 191K miles on it. Dealer said the trans was rebuilt at a local shop. It now has 195K miles. I have not serviced the trans, the excursion appears to have been serviced at ford dealer, as it has motorcraft wipers, batteries, paint dots on drain plugs etc.
Any comments or input would be appreciated. I am located in southern Indiana.