Electronic tach on 1586

The tach on the 1586 (80 or 81 model) was working then one day quite registering, then worked again and now hasnt worked in a few days. Mph was working when rpms didnt, but now that also doesnt work. The exhaust temp will still read out but the rpm, pto and mph arent registering. Where does it "drive" from? Would it be the display unit itself or the reading end of it? I will call the dealer tommorow to see what a new one costs and if they are still available. I have only had the tractor a month, and from the looks of an old brochure on the 86 series it looks like this display unit has been replaced and it looks like the ones the 88 series used. When i bought it from a small time dealer/farmer, he swore it was a 3000 actual hour tractor, but after seeing the tach is probably from a 88 series and it only works part of the time along with the other problems i have had i guess i got took. Live and learn i guess Thanks for any help or suggestions with the tach.

Do all digits light up when you turn switch on. If not, you may be lucky , there are two power sources to the tach, one is switch powered, other is live all the time. There is a inline fuse for tach down by the other fuses and may just be corroded. I always check for power and good ground at the connector that hooks into rear of tach. All pins are numbered, however I don't have diagram in front of me . I think number 1 is keyed power, two is ground and then about 9 is from inline fuse. At any rate, you need power to two pins. You have an rpm sensor reading off flywheel, and mph sensor reading off transmission gear. Not likely one of them if neither rpm or mph work. Original data center was not very reliable therefore they switched to the Dickey John one , similar to 50 series tractors. Check your grounds, connections and if all else fails the unit can be sent in for repair. We always sent ours to a place in Iowa, new ones are very expensive.

Thanks for the information. As of now the rpm reads 2 with the engine running and mph reads 25.9, the other day the mph was working, but now that has the 25.9 reading. The exhaust temp still seems correct and the the high exhaust reading is still set. I opened that cover and the 3 fuses look good, i have not run any power tests yet. I noticed under the cover someone must have been in there at one time because a heavy black wire bolted to the tractor is cut and i dont know where that went, one heavy read wire from a solenoid type thing is cut and two wires one red and one yellow with clamp on type ends are now hooked to the solenoid. There is also a plug in type connector that is not hooked to anything and dont see any other connector aroud. Everything was woking on the tach when i got it, then it start working once and a while and now only the exhaust is working. I will pull the tach and see if has power. I priced out a new one and they are 1300 at the IH dealer, thats not happening. They say they send them into a company for repair but wouldnt give me a price on what that costs. I am considering putting a mechanical tach on it from a salvage yard, if i can install the drive on the engine. I also went over to the red power site and did a search and they mentioned checking ground wires. Thanks again for the inormation.

The fuse is an inline one and not in the main fuse block. Seperate wire in same area though.

Checked that inline fuse you mentioned, fuse was good, but it had some gunk on the end, cleaned it up, put it back together and so far everything is working. Thank you sir for your help.

Good enough, now just keep your fingers crossed as those data centers can be very finicky.