WANTED Mercedes HHT

[Goran124]

I’m looking for a diagnostic tool mainly for the W124, but also for other Mercedes models from that era. What would you recommend?
Mercedes hht?

By the way, I had to replace the ECU on my 1995 W124 E280 — I installed another ECU with the same part number, but now the car won’t rev past 3000 rpm. I was told that the new ECU needs to be coded so it knows which transmission the car has.

Is that true, and which diagnostic tool can do that?

Thanks.

 

[gsxr]

Locating an original HHT with the proper software cartridges (ideally, the late ones, "A" and "B" that cover all chassis) along with working multiplexer is difficult at best, bordering on impossible. And expensive.

The best solution is buying a Chinese SDS, either C4 or M6, that has both HHT-Win support (HHT emulator) and also confirm the kit has a 38-pin cable with all 38 wires inside (yes, this is a real problem). Search the forum and read the long, detailed threads on this topic. It's complicated, and risky, as some vendors will ghost you if you have problems.

I'm not sure about the "coding" on a 1995 E280 with HFM injection. New modules come from the factory uncoded, and need to be set up when installed. However, I don't know what happens if you swap in a used module from a different car that is not code the same way. The HHT/HHT-Win may not be able to change the coding. Really need an HFM expert to chime in.

 

[R129 UK]

I'm not sure about the "coding"

Do we know if any component coding is possible / necessary with HHT era cars?

I'm fairly sure I read somewhere, quite possibly here, that is couldn't or did not need to be done.

 

[R129 UK]

I’m looking for a diagnostic tool mainly for the W124, but also for other Mercedes models from that era. What would you recommend?
Mercedes hht?

By the way, I had to replace the ECU on my 1995 W124 E280 — I installed another ECU with the same part number, but now the car won’t rev past 3000 rpm. I was told that the new ECU needs to be coded so it knows which transmission the car has.

Is that true, and which diagnostic tool can do that?

Thanks.

I agree with @gsxr's post.

What was the reason you replaced your ECU initially?


I have been using higher end enthusiast scanners for OBD2 Mercs and a knock-off SDS from China for my R129 for several years and have never even seen an HHT unit for sale, the closest is this which does not even include the HHT unit itself!!

MERCEDES W124/129/140/201/202 UTENSILE KIT CABLAGGIO TESTER HHT OEM 6511016099 | eBay UK

MERCEDES W124/129/140/201/202/463 UTENSILE KIT CABLAGGIO ELETTRICO ( ADATTATORE DIAGNOSTICO ) OBD PER TESTER HAND-HELD HHT + MODULO DI TEST + ISTRUZIONI D'USO OEM: - 6511016099. - 6511261006. - 6511500006. - 6511200006. - 6511235006. - 6511220006. - 6511160006. - 6511005099. - 6511014099. -...

ebay.us

 

[gsxr]

I have been using higher end enthusiast scanners for OBD2 Mercs and a knock-off SDS from China for my R129 for several years and have never even seen an HHT unit for sale, the closest is this which does not even include the HHT unit itself!!

$3500 USD for a full collection of HHT accessories is hilarious. That would be a high price even if the HHT was included! At least this seems to be complete, with A+B cartridges (plus some extra/duplicate chassis-specific modules), multiplexer, and "driving" extension cable, plus the nifty suitcase. But no HHT!

 

[R129 UK]

$3500 USD for a full collection of HHT accessories is hilarious. That would be a high price even if the HHT was included! At least this seems to be complete, with A+B cartridges (plus some extra/duplicate chassis-specific modules), multiplexer, and "driving" extension cable, plus the nifty suitcase. But no HHT!

Well, it has been on the market for 15+ months with no drop in the asking price (yet ):

Post in thread 'HHT (Hand Held Tester) 6511 0001 99 and Accessories'

Jul 29, 2024

Hello, does the software contain any user manuals etc.

I have never seen any documentation related to an HHT or HHT-WIN and I can't believe nothing exists somewhere out there...


Thanks.

I spoke too soon...

Just found this on eBay, it looks like €3000 for the cartridges, cables and documents, I can't actually see an HHT device in the photos

https://www.ebay.co.uk/itm/135125711549

Presumably it would go in this place?

It might be of interest to someone after OEM part numbers etc.

• R129 UK

• 

 

[gsxr]

Do we know if any component coding is possible / necessary with HHT era cars?

I'm fairly sure I read somewhere, quite possibly here, that is couldn't or did not need to be done.

Yes, it is possible, and necessary for a few, select modules on mid/late 1990's chassis. These early modules have rudimentary coding, I believe known as "variant coding", which is different than the SCN coding used on newer (early/mid-2000's and up) chassis.

One example I know of is the EGS/TCU used on the 210 chassis for 722.6 transmission. The coding tells the module what engine and gearing are used in that particular chassis. The coding is not selectable though - you cannot use the HHT to modify the coding. All the HHT can do is show current coding, and copy coding from one module to another. New modules from the dealer arrive uncoded and must have the code copied from the original module. This presents a serious problem if the original module is damaged and incapable of providing the source coding. Read this thread for a bit more info, posts 13-15.

Anyway. Yes, some HFM ECU's do require variant coding. Not all part numbers specify this, so I'm not sure if early modules don't need it, but later ones do? @Goran124 - we'd need to know the part number of your ECU to confirm.

Sample screenshot below. Note the 9-digit variant code. I do not know if the HHT is capable of changing the variant code on an HFM module, or if it can only copy coding from original module to replacement (like the TCU explained above), or if coding can only be copied to a new/virgin/uncoded module. I'm an LH-SFI Guy, not HFM.

 

[gsxr]

Well, it has been on the market for 15+ months with no drop in the asking price (yet ):

Yeah, that's going to be a tough sale. I wonder where the original HHT went.

I have some of that paper HHT documentation shown in the photos, it's largely useless. IIRC it just shows the codes for various systems, and that info is available elsewhere. The suitcase, MUX, and A+B software cartridges are the main useful items - for someone who already has an HHT. That assumes everything works, and there's no way to tell without both an HHT, and a few different 1990's cars to test with!

 

[Goran124]

I agree with @gsxr's post.

What was the reason you replaced your ECU initially?


I have been using higher end enthusiast scanners for OBD2 Mercs and a knock-off SDS from China for my R129 for several years and have never even seen an HHT unit for sale, the closest is this which does not even include the HHT unit itself!!

MERCEDES W124/129/140/201/202 UTENSILE KIT CABLAGGIO TESTER HHT OEM 6511016099 | eBay UK

MERCEDES W124/129/140/201/202/463 UTENSILE KIT CABLAGGIO ELETTRICO ( ADATTATORE DIAGNOSTICO ) OBD PER TESTER HAND-HELD HHT + MODULO DI TEST + ISTRUZIONI D'USO OEM: - 6511016099. - 6511261006. - 6511500006. - 6511200006. - 6511235006. - 6511220006. - 6511160006. - 6511005099. - 6511014099. -...

ebay.us

View attachment 227227

Two cylinders weren’t working with the original ECU. I got another ECU with the same part number that, according to the EPC, fits my car — and everything started working perfectly except for the issue that it won’t rev past 3000 RPM.

 

[Goran124]

Yes, it is possible, and necessary for a few, select modules on mid/late 1990's chassis. These early modules have rudimentary coding, I believe known as "variant coding", which is different than the SCN coding used on newer (early/mid-2000's and up) chassis.

One example I know of is the EGS/TCU used on the 210 chassis for 722.6 transmission. The coding tells the module what engine and gearing are used in that particular chassis. The coding is not selectable though - you cannot use the HHT to modify the coding. All the HHT can do is show current coding, and copy coding from one module to another. New modules from the dealer arrive uncoded and must have the code copied from the original module. This presents a serious problem if the original module is damaged and incapable of providing the source coding. Read this thread for a bit more info, posts 13-15.

Anyway. Yes, some HFM ECU's do require variant coding. Not all part numbers specify this, so I'm not sure if early modules don't need it, but later ones do? @Goran124 - we'd need to know the part number of your ECU to confirm.

Sample screenshot below. Note the 9-digit variant code. I do not know if the HHT is capable of changing the variant code on an HFM module, or if it can only copy coding from original module to replacement (like the TCU explained above), or if coding can only be copied to a new/virgin/uncoded module. I'm an LH-SFI Guy, not HFM.





View attachment 227252

Yes, i also have that information….that is needs variant coding and that HHT can do it…

 

[gsxr]

Two cylinders weren’t working with the original ECU. I got another ECU with the same part number that, according to the EPC, fits my car — and everything started working perfectly except for the issue that it won’t rev past 3000 RPM.

What is the ECU part number?

 

[Goran124]

Engine Control Unit A0195459732

 

[gsxr]

Engine Control Unit A0195459732

Yup, that's a late ECU, and it requires variant coding. HHT-Win (on SDS / Star Diagnostics) should be able to tell you the original coding, and what coding is on the replacement ECU you installed.

The big question is, can HHT-Win change the coding, or only copy from old to new. Try it please post the results here!

 

[R129 UK]

@Goran124 if you get the coding done via HHT-Win, please post some screenshots here. I would like to see how this is done / how easy it is. Thanks.

 

[Goran124]

@Goran124 if you get the coding done via HHT-Win, please post some screenshots here. I would like to see how this is done / how easy it is. Thanks.

I dont have HHT and i think it will be hard to get one…but dealership has it but im probably not going to be able to record it!

 

[gsxr]

I'd be surprised if many dealerships still have the old HHT. The vast majority use the HHT-Win emulator that is available in SDS, and all dealers us SDS now. Either one will work fine (original HHT, or HHT-Win on SDS).

 

[gerryvz]

REAL HHTs very rarely come up for sale anymore, and when they do they range from $2K for beat-up units with few to no accessories, to $5K+ for better units. Expect to spend at least $5K for a good unit with the proper cartridges and accessory cables, etc.

You would be surprised - a lot of dealers do hang onto old diagnostic equipment, others do not. A lot of independent shops have bought up HHTs over the past 10-15 years. They do seem to be much more common in Europe than they do here in the US, at least for used units for sale. If you do find one for a decent price, that's a unicorn and I'd snap it up on the spot.