The border is located about 40km east of Jolfa. Go through Jolfa, arrive at the roundabout at the east of the town with the railway next to it. Do no go under the railway, but go north on the narrow road which appears to go nowhere. Come to a police block, pass through, over the level crossing and then the 40km road to the border starts.
This road is spectacular. Leave your camera in its case - there are watch posts all over the place. You're surrounded by truly stunning rocky mountains, with the fast flowing river to your north.
Iran (Time to process: less than an hour)
Enter the border compound. Show your passport to enter.
Proceed to the office in the middle of the compound (with a shelter in the front of it). Go to the cubicle at the far end on the right-hand side, to have the visa stamped.
Visa stamped, take the vehicle to the far two Portacabins at the opposite end of the fence to where you came in. Go in the furthest Portacabin. Offer the Carnet pad and your passport. All the paperwork is processed here.
Armenia (Time to process: 8 hours)
Go over the bridge. CIS border guards (Russian soldiers) check your passport on the bridge.
Continue to the next batch of CIS border guards (Russian soldiers again). They look over the vehicle, removing all traces of cigarettes. Then proceed into the entry compound.
Go into the customs office at the right-hand side doors on the west side of the building. Go to the first cubicle on the left, the passport check. Visas can be purchased here (3 day visa for US$20). Then go to the next-but-one cubicle to complete the customs declaration form in duplicate. All paperwork is in the Armenian language. There was an Armenian customs official who spoke excellent English on my entry who assisted greatly.
You are then told to bring your vehicle through the gates into the inspection compound at the south of the hall. The customs check the vehicle, and then enter the vehicle's details in the computer.
There is an ecology tax, based on the vehicle weight. A sort of Road Tax (VED). And there's a customs surcharge. For me, the combined charge was US$65. (There is a bank in the customs hall, which changes money. It is only a rumour that Securicor send a large articulated truck to collect their takings, three times a day. There's only two.)
You receive 8 pieces of paper, having signed 15 (the triplicates need individual signing). Don't loose any of them as they are essential if you want to leave with the vehicle.