One other WILD possibility is the intermediate shaft and inboard axle joint (pass. side) is coming apart and for some reason is catching in the 'forward selection. Replaced over 6 sets in the last 2 years (at dealership) and each failure had it's own unique symptom , I'm guessing because of all the different driving 'styles'. The splines where they connect get damaged over time and I have not seen a consistent wear pattern among them yet. One other thing to mention , if you end up replacing the trans , I would recommend getting a Honda re-man , or a really good warranty if re-built by any other than Honda. If you have any service history with your Honda dealer they may offer some 'goodwill assistance' , couldn't hurt to ask especially if you bought it there and they want you to buy from them in the future.
I think it's possible that a bad mount (usually the front and side , poss. both) would agravate the poss. wear , but I have yet to see that be a cause of no reverse only. Honda has basically six main items in their diagnostic 'flow chart' and all are internal failures requiring trans disassembly(basically-overhaul). Do you know FOR SURE that overdrive is working ,along with proper torque converter lock-up function? AGAIN I stress my idea is a very SLIM possibility, I'm just curious (maybe the other guys have a thought on this?) if you have a whine ONLY in reverse - I think of pump failure or torque converter , but both of those should have some effect on forward gear function. [[[[[[[[[[[[[[........ aLSO JUST CHECKED ....-some '04 Odysseys were included in their 2nd gear inspection recall. You can post vin or check at local dealer to see if it was done on yours (if applicable). The VIN range for '04 models begins 5FNRL18--4B000001 thru 5FNRL18--4B051620 , if you are the original owner , you should have received a letter a long time ago. Good luck.
Hi Thank you for your time you are spending on this.Now yes it does have overdrive,torque converter seems to lockup.the van drives perfect,just no reverse.We bought the van it had 7500 miles on it.it was a lease van.bought it from honda dealer.not sure about recall we never got letter in mail. Vin # 5FNRL18614B010136 again Thank You for your time
'VIN' status shows the recall was completed. Selling dealer was Sierra Honda. Did you buy it back in '05? mileage actually 7500, or was that a typo, and you bought it more recently with 75,000? It shows a name 'C----A as the original owner , but nochange for 'current' owner. Doesn't really matter since the only applicable recall has been completed, but if any new ones come out (I hope not) , you will not get the letter unless that is changed.------Back to your initial question , if after the axle& intermediate shaft are checked , no problem with them is found , then unfortunately you will need a trans. I stand behind my rec. of a Honda re-man because there were several internal updates that may not be done at an aftermarket trans shop. Honda (at least at all dealers around my area) does not allow 'in-house' rebuilds.