Hydronic Heater D5WZ Module Question

[Mymax]

Hi, I was curious if anyone has a suggestion for my locked D5WZ hydronic heater module.

I have a 6.6 Duramax, 2006 savana 2500 van I bought new and the FOH has been working perfect up until last winter. What I think hurt it was I had a bad battery I was charging over and over again. [my bad] Also, GM didn’t tightn the new battery cable to the terminal block under the hood causing some serious noises and gauges bouncing around.
At that time the heater would start but smoke a lot and that never happened before. The battery issue must have locked the module up I guess because shortly after that it just wouldn’t start again.

This winter turned cold now and still the heater wouldn’t start so....
I replaced the module from a complete heater I bought on eBay the other day from a 2010 Savana and it is now working again. GM wanted $1600 cad for the module - $1900 for the complete heater.
I bought from eBay complete unit for less than $300 cad delivered and the module works... think I got lucky

Is there anything I can do to unlock my original GM 252360 module? Good for a spare or could sell it I guess if the module could be unlocked.

Can a Espar dealer/techs unlock this as they are just down the road from me I see.

Thanks for any info.

 

[LBZ]

So was this a factory optioned heater or just something they put in?

I’ve locked up TSL and thermo 90 Webasto before but never an espar. In the service manual for the webasto they had a procedure of turning on and pulling fuses to get it to reset. I would like to think espar does the same. I’d suggest a call or stopping in at an espar dealer to see what they have to say about it.

 

[Mymax]

Yep, was factory and worked so good for 12 years or so. The heavy smoke I believe was when the voltage was too low and the igniter couldn’t fire the diesel properly. With good batteries etc and this other module it’s burning clean and working good.

I did read some trouble shooting on this heater and once it gets hard locked it needs software/diagnostic tool to unlock it again.

This gm branded Espar module is proprietary gm secret and gm dealers don’t want much to do with it except sell us a new one.

For the heater to run your gm has to be running with low coolant temp, 1/4 tank of fuel and an ambient temp of 4C or colder. Only then will it send a signal to fire up so it’s very hard to do any service/testing on the system.

I was just hoping someone new what software or if an Espar controller/code reader would reset it.

I will stop in to the espar dealer here and ask if they can test this gm module...:thumb::thumb:

Thanks

 

[ShopSpecialties]

There is diagnostics in the Tech 2 for the heater and I would try that first.

 

[Mymax]

Thanks guys for your help and confirming the tech 2 may have some diagnostics.

Yes, we’ll last year the issue with the batteries and cable replacement gm told me I needed a new heater so I took their word on it after they quickly looked at it.

This year (a couple weeks ago) when I took it into a different gm shop I explained the issue and asked the young diesel tech if he could check it out with tech 2. I had read from this great site that there was a diagnostic (test aux heater) section so was hopeful but all he did was read codes. There was one “comb blower motor circuit open” but when I asked him if there was a section to test this heater he didn’t even want to discuss it...he was done, unplugged

Anyway, I got home that evening and slid the module out, tested the motor and it run, tested fine as did the glow plug and flame sensor.

I guess I could spend another $140 if I was be-able to find a gm tech that would want to help, spend the time to at least look for the diagnostic section within Tech 2:coolspot:

I’m starting to think maybe tech 2 only will test basic functions, a signal to turn on but maybe that’s as far as it goes? No Reset? It is possible the board Is fried but very unlikely so it’s really the biggest reason I wanted to do more searching here.

Thanks ShopSpecialties, have you used this diagnostic section and can you say if a “reset” is possible within this tool?

:thumb::thumb::thumb:

 

[ShopSpecialties]

Thanks guys for your help and confirming the tech 2 may have some diagnostics.

Yes, we’ll last year the issue with the batteries and cable replacement gm told me I needed a new heater so I took their word on it after they quickly looked at it.

This year (a couple weeks ago) when I took it into a different gm shop I explained the issue and asked the young diesel tech if he could check it out with tech 2. I had read from this great site that there was a diagnostic (test aux heater) section so was hopeful but all he did was read codes. There was one “comb blower motor circuit open” but when I asked him if there was a section to test this heater he didn’t even want to discuss it...he was done, unplugged

Anyway, I got home that evening and slid the module out, tested the motor and it run, tested fine as did the glow plug and flame sensor.

I guess I could spend another $140 if I was be-able to find a gm tech that would want to help, spend the time to at least look for the diagnostic section within Tech 2:coolspot:

I’m starting to think maybe tech 2 only will test basic functions, a signal to turn on but maybe that’s as far as it goes? No Reset? It is possible the board Is fried but very unlikely so it’s really the biggest reason I wanted to do more searching here.

Thanks ShopSpecialties, have you used this diagnostic section and can you say if a “reset” is possible within this tool?

:thumb::thumb::thumb:

I am not sure about a "reset" but the Tech 2 can turn on the heater manually for testing.

 

[Mymax]

Thanks Shop, appreciate your knowledge