Blown ABS ECU - how not to do that etc.

[martinwcox]

So, I may have blown up my ABS ECU in my M923. In talking with a guy at Haldex who it turns out, put together the kit for the MWO for the ABS on the M939 Series truck.
He told me that if the truck is shutdown incorrectly it’s likely that you will send a 100V+ spike down the 24v line and fry the ABS ECU. (I may well have done this by accident.)
Incorrect shutdown simply means, turn off the battery switch before shutting down the engine. The Protective Control Box(PCB) has a 32V diode but that fails and then subsequent incorrect operation causes the damage. The PCB still works but now it’s not stopping voltage spikes.
I am thinking may be add a DC-to-DC converter on the power lines to the ABS ECU and actually add some real protection to the only electronics in the entire truck.
Any other options or ideas welcome.

 

[wsucougarx]

Good to know. Thanks for sharing as it may prevent someone else from doing the same thing.

 

[M35A2-AZ]

I talked to him also and he told me the same thing.
You may check ebay or check with GIJoeCzar here on SS.
If not try 91w350 in KS. if that all falls I may have a place I can check to see if they have any.

You may check the two fuses that are under the dash right be the steering column. They are in-line fuses.

Good Luck.

 

[ARYankee]

Wow. That is totally different from the TM. Here is the section on stopping the engine.

I wonder which way is correct.

 

[tie6044]

I think they are saying the same thing, battery switch is shut off last.

 

[ARYankee]

I think they are saying the same thing, battery switch is shut off last.

If so then the OP needs to change his original post because the OP has the battery switch being turned off before you shut down the engine. That is why I posted the engine shutdown procedure from the TM. I just want to figure out which is correct, if there isn't an error with the OP's original post.

 

[EMD567]

The OP did turn off the battery switch before the start /run/kill switch. You can do that on an 800 series, and get away with it(not a good idea). It is a big no no with the 900 series.

 

[Derrickl112]

If so then the OP needs to change his original post because the OP has the battery switch being turned off before you shut down the engine. That is why I posted the engine shutdown procedure from the TM. I just want to figure out which is correct, if there isn't an error with the OP's original post.

Incorrect shutdown simply means, turn off the battery switch before shutting down the engine.

The OP doesn't need to change anything.

 

[ARYankee]

The OP doesn't need to change anything.

I see it now. I was totally misreading it. I apologize to the OP and every one else. I guess I was having one of those moments.

 

[jw4x4]

I will be watching this thread to see if someone figures out a way for actual protection. In the meantime, I will be extra careful on the shutdown sequence.

 

[martinwcox]

I have a thread in the 5 Ton Mods forum specifically addressing adding better protection, just need a few experts to validate my idea.

http://www.steelsoldiers.com/5-ton-mods-hot-rodding/91110-abs-ecu-protection-ideas.html

 

[jedawson1]

Where is the protective control box? I'm pretty sure I have used my one life and the next mistake will be expensive.

Would like to look at the PCB to reset the safety.

 

[martinwcox]

In the engine bay on the firewall drivers side, rectangular black box.

 

[jedawson1]

Thank You, do you know if this has to be replaced or does it have a reset? I'm going home on lunch to check mine out to see if it's been activated. I'm pretty sure I did an incorrect shutdown once.

 

[martinwcox]

From the conversation I had, it would seem that the protection diode fails, so that would point to opening up the PCB and replacing it (diode), I have never opened a PCB up, I think there may well be some threads related to the PCB that may help.

 

[wsucougarx]

I bought a brand new control box directly from the gov't manuf (Southern Automotive) on ebay. They have them listed for only $133. Considering others are selling them for well over $200.

 

[martinwcox]

Mike,

Thanks for that, did you ever take one apart?

M.

 

[martinwcox]

Possible Protection 'Brick'

I found this on the web, funny it's a company localish to me!

http://www.hdm-sys.com/pdf/hdm_vtp10-24_specs.pdf


I have a call into the vendor for pricing and a call into Haldex to find out what the current draw is with both valves on (modulating.)

 

[martinwcox]

Well the device I originally found was $150 and only good for 10A, so I found one of these for $50 which I will wire into the supply line from the PCB and protect all the circuits fed from that point, good for 150A load and clamps at 31V.

NORTHERN TECHNOLOGY 24V SURGE PROTECTOR DCB-24SM

 

[martinwcox]

I did get an ECU and valve assembly from ebay. The 15A fuse blows as soon as power is applied, unplugging the ECU, fuse is fine so st least that rules out a short to ground in the cable but confirms the ECU is a gonner!

I am about to add a surge protector to supply both the unswitched and swiched supplies to the ECU and hopefully remediate the issue.

I talked to him also and he told me the same thing.
You may check ebay or check with GIJoeCzar here on SS.
If not try 91w350 in KS. if that all falls I may have a place I can check to see if they have any.

You may check the two fuses that are under the dash right be the steering column. They are in-line fuses.

Good Luck.