TELSTA A28D Bucket Controls Acting Up - Vehicles

Hello everyone and thank you for allowing me to visit your forums.
Recently I purchased a 1994 F-450 with a A28D Bucket on the back for the purpose of changing out light fixtures (under canopy / light poles) at my customers locations. Problem I'm having with my truck is that the controls on the boom are acting up intermittently. The controls down low in the right rear panel all work fine. The truck came with the complete TELSTA owners / service manual which includes a complete wiring schematic, but I'm still lost of where I should start.
Anyways, I was hoping to pick the brains of the guys that work on these trucks and maybe they will be able to steer me in the correct direction. I'm hoping that this is a common issue and that there is a common fix.
Thank you in advance for any and all help that is sent my way...

Any luck finding those wiring diagrams?

It's probably the switches are worn out. They get used a lot more than the truck mounted switches. I have to replace the boom switches on our boom truck about every 3 years. The switches are very cheap and easy to repair on our.

I have a complete set of manuals which includes wiring schematics. I am a NIASE (I'm dating myself) certified mechanic and an accomplished Experimental aircraft builder, but these wiring flow charts for this truck are enough to make you drink. Anyways, I believe I found the problem. Looks as if a couple of the spade connectors in the main control box are compromised. I'll be taking digital photos of the connections and then systematically replacing all the connectors 1-by1. Must be over 100 in this box.

Replacing the switches wouldn't hurt. I'd also like to replace the 3 small relays in the main control panel where the boom mounts to the bed of the truck. Can you please share with me where you buy your parts.

Thanks in advance.

Square D and the owner of the local place is a customer of mine. I just bring the old ones in and they give me the new ones.

We recently purchased a 2000 e350 with the Telsta A28D lift and had similar problems. Ours acted up when running the emergency 12v pump. I would have full control at the bottom in emergency, but only half at the top. If the van was running or if a charger were connected I would have no issue's as voltage was up. The problem was too much resistance in the wire that connected to the basket control override switch at the lower control box. Power had to run from the tower to the rear controls then back to the tower up the boom to upper controls and back down to the tower. the fix was installing a relay in the tower control box to eliminate the long wire run ( I can explain in more detail if needed). I am now not worried if I need to run the lift on the emergency pump. Problem solved...

hey guys wondering how to get ahold of a manual for a telsta a28d boom

Where can I find a set of the wiring manuals?

Help me relay this 94 telsta I love it and I went to deep cycle battery but still choking volts at upper can u email the diagram or send it here Thanks

Post a email addy and I'll do what I can.....

You will need to find the wire in the tower that has power when the override switch is in normal posistion. This wire sends power up to your controls in the bucket. Due to power required to operate the solenoids when battery voltage is low as in emergency operation with 12v hyd pump running voltage drops to low for solenoids to function. This is caused by the resistance in the common power wire running from the tower to the rear of the van then back to the tower and up to the controls back down to the solenoids. By adding the relay in the tower you eliminate the resistance in the override circuit that causes the voltage drop. The relay will close upon the override switch activating, then the power circuit will be switched in the tower. You will have to meter this out and have electrical knowledge for this to work. I am assuming you have the a28d mounted on a van with the controls on the rear door if your having this voltage /control issue at the basket.

Yes hello, personal Thanks for the info I have a 94 f-450 and a telsta work box but am noticing the same tower box and located power and note that i have aswitch in cab that opens to 13.5 , so i will take the advice and run a normally closed relay for only upper and then when ineed power and lower ill switch to close lower and open upper Thanks.

I have a complete set of manuals. They included the following:

1) Operator's Manual
* Part #T-76263

2) Service and Repair/Parts Manual
*Part #T-76264
This includes all hydraulic and electrical schematics

3) Tools & Accessories Catalogue
*Part #T-14134

$75 shipped

Seems to me I am having trouble only in the electrical upper so If needed I will contact you in the future Thanks Sir.

If you haven't gotten this figured out yet, you might talk to some of the guys I work with that recondition bucket trucks. The number is 800-867-9177. I'm sure they could give you a few ideas and if nothing else, the info is free...

hope this helps

Hello, I just decided to get me a bucket truck , a 97 Ford with Telsta A28D, was wanting to see if someone could tell me where to get some user and wiring /service manuals for this unit. Also, I have already discovered an issue with it. It has Onan 4500 gen w/ battery for emergency back-up use- Unit starts fine from gen. or at back panel and the controls operate bucket smoothly but when you flip switch from override to normal to be able to contol from bucket ,it kills generator. Any ideas?? Thanks, WM.


I have a 1993 Telsta A28D and I need the relief valve. I no its a RV3 but not sure what the part number is or what pressure rating it is. Anyone have a manual on this that could help me out with the part number??

I have a 1996 with a lot of issues lower controls all work. But boom does not go down you can hear the pump working but doesnt move but goes down with emergency button. All Upper controls do the same thing. A few times things worked intermittently. Any help would greatly be appreciated thanks guys

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