DIY: Replacing factory Espar heater with new off-the-shelf

kentonius

enough to be dangerous...
This will be my attempt at documenting the installation of a new, off-the-shelf Espar D5WZ.

Background: 2006 158" Passenger with Rest, Booster, and Aux (7-day timer) installed from the factory.

Issue: Factory installed Espar failed all tests to the ECU, determined that the ECU is bad and needs to be replaced. However, it's difficult to find a replacement sprinter ECU piece (end cap with the plug attached.

Solution: Others have attempted to "de-pot" the board, and then try to fix the actual circuit board. I will go a separate route, and replace the unit in its entirety with a new D5WZ ordered from Heatso.com.

Steps to overcome: There have been some threads on the issue, but the programming and wiring *may* be different between the factory installed Espar, and this off-the-shelf unit. Specifically, the integration with the factory systems *may* not function as installed. 7-Day timer may work to read fault codes.

Goal: Install the new Espar, and be able to utilize the 3 main functions:
1. REST - Espar independent, just need to ensure that the electric coolant pump still works post engine shut-down to circulate the hot coolant.

2. Booster - Espar required to operate at cold-engine start-up/warm-up. Not necessary for the Espar to trigger the electric coolant pump (?) as the engine driven pump will circulate the coolant preventing an overheat condition in the Espar.

3. Aux (7-Day timer) - Espar required to operate with engine off, no key in ignition. Definitely necessary for Espar to trigger electric coolant pump and HVAC fan control. This one I anticipate being the most tricky.
*** I could care less about programming the timer, I just want to be able to utilize the function where I can start the heater for 120 minutes to provide heat to the front cabin.***


Assumptions:
1. Espar ECU will be relatively the same in that it will control all the same functions of the Espar - from start up tests, fuel pump, safety measures, and shut down procedures.

2. Electric Coolant pump is independent of the Espar for Rest to function

3. 7-Day timer will read fault codes of the new Espar

4. I will be successful. I hope.


And to start off, I've attached pictures of the new Espar next to the old one. As you can see, mine had the second pigtail that plugged in to the van. I'm really curious if I can just tap into this connector to trigger relays (Terminal 15) for the Aux function to work.

The new Espar is labeled with the Audi/VW brand. Same Espar model, different reference number. Same plug to the van harness, with the same color wires in the pin out.

Comments, suggestions, offers to help are all welcome.
 

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kentonius

enough to be dangerous...
One more picture of the plugs, showing the same color wire locations for the old and new.
 

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vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
K: u may not have t15 with your setup given you already had the oem ability to fire off the furnace w/o the engine running. Question is, did Audi/VW need to have a t15 type circuit?? This is the circuit on ours which don’t allow the furnace to work unless the engine is running.

The aux coolant pump does need to run when the engine is running for the Espar to work correctly and not over heat. But, it should already be running anyhow assuming the pump itself is not faulty.

Just for giggles, without putting it in to the coolant circuit, if you simply plug it in, hit the 7day timer on button, and then walk over to the heater, can you hear the little internal fan in the furnace spin up? This would be my first step. Turn it off immediately after you do the test as you don’t want it to actually fire without coolant.

From there it should be as simple as wiring in a relay which gets closed to kick off the coolant pump. Personally I recommmend wiring it as a single pole double throw to separate the circuits and prevent any kind of back feeding.
 

VinceP

2005 158" High Roof Pass.
I am planning to the EXACT same thing. I have the same van ('05 158' Tall passenger, With 7-fay timer, rest, boost, AND rear heat exchanger). I was looking at Heatso site and wasn't sure which Espar to order. Did you reach out to them to ask for a Sprinter-specific before you ordered? Please let us know how it goes.

Anybody knows here what is the purpose of the second connector that is missing on the new unit?

Thanks

Vince
 

vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
Anybody knows here what is the purpose of the second connector that is missing on the new unit?

Thanks

Vince
90% sure it’s for the aux coolant pump only. Potentially also for the atc blower motor, but probably not.
 

VinceP

2005 158" High Roof Pass.
What encourages me is that the Connector is identical, even with the same color wiring. Discussion has been all about D5 heaters differences, but this is a specific D5WZ. Which is what we have in ours. We clearly don't care about the T15 circuit. Just need to make sure the Aux pump is triggered, and the Blower fan comes on. The 7-day timer is Espar-specific and common to all their heaters.

VERY interesting thread.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
This might help?
OEM Sprinter manual with Part Number match to my 2004 unit.

The 2-pin plug is labeled “Dosing pump” but I’ve never traced it.
May help to compare pinouts with your new unit?

The only control input on the 8-pin plug is the Terminal 15 signal, so I’d expect that the Sprinter simply energizes that pin when it wants the heater on. How the 7-day timer works isn’t shown, but there are splices and relays hacked into FB#1 under my dash that I suspect are related to my 7-day timer... I would expect it’s the ATC that powers the coolant pump when you press the “Boost” (bacon) button, since it also needs to be able to do so for the REST feature, so the “simple” thing is for the 7-day timer to energize the same wire, and let the Espar manage the fuel dose pump to regulate its heat output.
(just guesses, but that’s how I’d do it... ;-)

Happy hunting,

-dave
 

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Nautamaran

2004 140” HRC 2500 (Crewed)
Yeppers.. so now someone needs to find where b3 goes on the crew models Sprinters equipped with the 7 day timer.. to the component or to a relay?

Mind anyone reading this without the crew model you will need to wire separate relays for the other components.
The dosing pump isn’t a simple on/off signal, it pulses to control the fuel flow rate. So the B3 connector can’t be running a relay?

I’d check the new unit’s wirig diagram, but expect you’ll just splice into the green wire on pin 4 on the new unit and connect to the B3 pigtail from the old unit (as shown in the wiring diagram on page 6)

-dave
 

vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
The 2-pin plug is labeled “Dosing pump” but I’ve never traced it.
May help to compare pinouts with your new unit?

-dave
There's some conflicting info here.. and that's probably because Espar put together this one document for both the Heater Booster and the Auxiliary Heater where the HB has no extra plug (B3) and the AH version of the heater does ..

Pin 4 on Heater Booster plugs control the dosing pump. Heater Booster folks don't have a separate plug.

This could create a little more complexity if it does indeed drive the fuel pump on your guys' furnaces as the new VW one you have will drive the pump from the primary S2 plug.

The only control input on the 8-pin plug is the Terminal 15 signal
-dave
On the Heater Booster models it's T15 and D+ Dynamo for the control inputs. Pins 6 and 7 on the primary plug (S2). For your guys' I was thinking T15 may be absent and you would only have D+Dynamo. This is another potential problem with this document being for two different furnace types. T15, as with all the other T15 references across our Sprinters, only allow components to turn on when the motor is running. I guess there's a chance the 7 day timer would kick off both the D+Dynamo and the T15 :idunno:

The easy way to tell if the fan and coolant pump kicks on irrespective of the the heater would be to hit the on button and turn on the fan and feel the aux coolant pump.

Okay Kentonius, apologize for taking away from what you're trying to contribute here. I was just trying to help a bit based on my experience in working with a bunch of these things... But I've never traced all the wires for one with the extra plug. Press on!
 
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vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
The dosing pump isn’t a simple on/off signal, it pulses to control the fuel flow rate. So the B3 connector can’t be running a relay?

I’d check the new unit’s wirig diagram, but expect you’ll just splice into the green wire on pin 4 on the new unit and connect to the B3 pigtail from the old unit (as shown in the wiring diagram on page 6)

-dave
Yes, completely understood it's not a simple on off... There is significant variation in the signal based on many different parameters.

I'm not convinced B3 is for the dosing pump. Why label it in two different locations and what pin 4 used for on the Auxiliary Heater models??
 
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kentonius

enough to be dangerous...
For what it's worth, here is my old espar with the separate connector. It had both a brown and a purple wire, but if I recall right, only the purple wire was connected to the van harness. This picture is of the harness contained WITHIN the espar itself. The big plug goes into the ECU end plate.
 

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kentonius

enough to be dangerous...
I am planning to the EXACT same thing. I have the same van ('05 158' Tall passenger, With 7-fay timer, rest, boost, AND rear heat exchanger). I was looking at Heatso site and wasn't sure which Espar to order. Did you reach out to them to ask for a Sprinter-specific before you ordered? Please let us know how it goes.
Vince - I talked with VanSki and he mentioned the Heatso folks. He also let me know NOT to tell them it was for a sprinter as they would refuse to sell to me.

This is the unit that I ordered: Espar D5WZ

It ended up being about $600 after GBP->USD conversion. That was with FedEx shipping that had it to me in 2 days. From the UK. Crazy.
 

vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
K: Did it happen to come with a wiring diagram? If so, take a picture and post it up. I feel a little obligated to see this through since I did direct you to this heater. Truth be told, I'm interested in getting it to work for you as well; I'm tired of hunting down working Control Units and having to rebuild.
 

kentonius

enough to be dangerous...
K: Did it happen to come with a wiring diagram? If so, take a picture and post it up. I feel a little obligated to see this through since I did direct you to this heater. Truth be told, I'm interested in getting it to work for you as well; I'm tired of hunting down working Control Units and having to rebuild.
It only came with the heater unit. Otherwise, the box was empty.

...makes things more interesting...

I appreciate the help too!
 

Midwestdrifter

Engineer In Residence
The violet and Brown should be the coolant pumps power supply.

If the ATC supplies a 12V+ on signal (yellow wire on external harness) then you can just wire that straight to the new D5. Then connect up the aux coolant pump directly to the D5.

Since the ground is common with the van, the purple wire may just go the ATC to trigger the coolant pump?

Some of the colors on the factory unit don't match my d5, however the pin-out is the same, just different colors for some wires.
 
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vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
After reviewing multiple d5wz pin-outs (I could not locate the exact pin-out for the d5wz-252163050000 version) it appears all of them are pretty much the same. I'm only stating this because if there are differences I wanted to make sure it didn't have anything to do with the wiring.

After taking a closer look at the last picture the OP put up (img_0534) the purple wire which leads to that plug is coming from pin 11 on plug B1. B1 plugs directly into the Control Unit. I couldn't find a single pin-out with anything coming from the CU @ pin 11 on B1. This is for something different, outside the normal scope of components, the CU communicates with. Either a signal to the ATC or to the coolant pump. At least that's my best guess.

I have verified that if the Control unit is not responding neither the ATC or the coolant pump get kicked on. So the heater has to go through it's normal startup procedure, validating all internal components, for those two components to be kicked on. This leads me to believe the signal goes to the ATC which then kicks on the coolant pump and the ATC (probably via the the second pin available which enables what we all know as REST functionality). If someone with the crew version and 7 day timer could verify only the first three settings on their vent motor control works when they hit the 7 day timer, then we can validate that's where the wire lands, most likely..

I'm thinking all he has to do is jumper from D+Dynamo (yellow wire) to the purple plug wire, plug the thing in, hit the bacon button, and he'll be off to the races.
 
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VinceP

2005 158" High Roof Pass.
Just verified mine this morning. (2005 Passenger)

I have a Non-Functioning Espar that hasn't worked for years, and a no good coolant pump (i have a new one ready to install)

When I press the Bacon button on the 7-day timer, the first thing happening is the Cabin blower kicks in speed 1, "120" appears on the display, then after 3-4 seconds, I hear a relay click in the dashboard, and the blower stops. The 7-day display remain at 120, but nothing else happens.

If my coolant pump is no good, maybe this prevents any further sequence?

We'll get there!
 

Patrick of M

2005 T1N 2500 (NA spec)
Just verified mine this morning. (2005 Passenger)

I have a Non-Functioning Espar that hasn't worked for years, and a no good coolant pump (i have a new one ready to install)

When I press the Bacon button on the 7-day timer, the first thing happening is the Cabin blower kicks in speed 1, "120" appears on the display, then after 3-4 seconds, I hear a relay click in the dashboard, and the blower stops. The 7-day display remain at 120, but nothing else happens.

If my coolant pump is no good, maybe this prevents any further sequence?

We'll get there!
Almost for sure your Espar fan is stuck, but before you pull the unit, hook up the diagnostic wire to your 7day timer, that will tell you a couple of things, 1. That the Espar ecu is working/not. 2.probabbly the fan is stuck. The fan is the only moving bit in the espar , so sitting for years is not a problem other than the fan. The diagnostic wire to the 7day timer is really helpful, makes troublesh A breeze. Kind of stupid that it wasn’t wired in OEM.
 

VinceP

2005 158" High Roof Pass.
Thanks Patrick,

Do you have the diagnostic wire hook up procedure handy? I can't seem to find it.

Vince
 

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