- My model of MX-5 is: 2002 NB2.5 1.8vvt
- I’m based near: Gloucester
- I’m looking for technical help or recommendations on: Correct voltage outputs for EGR controls from ECU
Hi there! Hopefully somebody can help me. I’m not too knowledgeable on ECU issues and I suspect that mine is fu#*%d
So the problems are…
Idle droop and occasionally cutting out.
Running rich
Codes are…
P0172 - System too rich
P1498 - EGR Valve Motor Coil ‘3’ Open or Shorted
What I’ve done so far…
Cleaned air filter
Adjusted mechanical idle control
Cleaned intake manifold
Cleaned EGR pipe
Replaced EGR
That didn’t fix anything so I got a multimeter to check the wiring going to the EGR and found that my ECU had been messed with previously. A couple of the bolts on the metal casing hiding the ECU had already been drilled out. So I suspect a previous owner knew all about this issue.
So here’s where I need some help. The voltages coming from the wires related to the EGR are as follows…
W/R = 11.5v
P/B = 11.5v
W/G = 11.5v
P = 0.01v
LG = 0.01v
Also note that my battery without the engine running reads 11.5v, which is low, I know. With the engine running its 14.2v, which is okay. Could I have a grounding issue or do I just need a new battery?
Any help on this would be mega appreciated! Are these figures okay? What do I need to do next?
For reference, the pins in question are highlighted below…
Cheers!
It sounds like ECU Dan
There are three EGR coils and three associated chips on the ECU.
When the EGR lets go it usually takes out the top chip P1499. With your code it will likely one of the lower pair(P1497, P1498). You need to get the ecu out to check.
Given the other code and symptoms there may be water ingress into the ecu/wiring.
If that is the case, the EGR may be OK but associated water damaged components on the ecu?
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Thanks! Yea I’ve tested the EGR and it functions fine. Unfortunately I have traced the issue back to the ECU 
there’s no drop in voltage or increased resistance between the ECU and the EGR. So dodgy wiring isn’t the issue. Soooooo I guess I just need to confirm whether those ECU voltage readings are bad or not. ???
I’m just guessing that the 0.01v readings are the problem. Should it be something like 5v?? I don’t know 
I’m not sure mate to be honest but if the EGR is functioning without issue and there appears to be other, non-associated issues, you need to do a visual on the ecu pcb. Sounds like you are there with access to the ecu, so just five philips bolts to undo and it will be in your hand.
Feel free to put up photos of the board on the forum or contact me privately; I like playing with this stuff:-)
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Ahhh sorry I get you, open it up and have a look! Okay I’ll get it open this weekend and grab some pictures. That would be really helpful thank you!
Okay I finally got some pictures! Sorry for the wait. Hopefully they are clear enough for you to use!
It’s not that easy to see detail but what I can see appears very clean and undamaged.
I assume there is no burning electronic acrid smell or any damage that my old eyes and a limited photo are not seeing/showing?
Nope no burning smell or any damage from what I can tell. Would you by any chance know what part of the ECU is responsible for the EGR coils? I’ll get some photos that are closer up if that helps. Thank you very much for looking!
In your second photo, top left beside the connector joins with the board. There are three quite large chips, a pair followed by a single. The usual code is a P1499 and that seems to destroy the top part of the single lower chip, bottom end in photo. The other two I guess would blow with a P1497 or P1498 where there was a catastrophic spike through the EGR coil system. Your EGR chips all look good, so a little strange to get that error.
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Hmm okay. That is a little odd then. I’ll have a closer look at those chips in better light for any signs or smells of damage. I might try and get a cheap matching ECU from a breaker car without error codes. Just to plug it in and see if it solves the problem before buying a full ECU, immobiliser and key set. Thank you again for your help it has been super useful 
Do those three chips have numbers on them or are they blank? Seems likely they’re some generic driver chip so it would be fairly simple to change them if they can be identified. It would be a shame to bin an otherwise good ECU.
That’s an even better idea!
The top left chip is numbered T710
Top right is T720
Cant see the bottom chip’s number unfortunately from this photo
If replacing these chips could fixes my issue that would be great. Are there any nacks to removing and replacing a chip that I should know before I try yanking one off? 
That latest picture appears to show damage to the single chip talked about in a previous post. The bottom right of it in this picture seems to show contact and pad damage.
The three chips are all the same in my opinion. When I say my opinion, my best efforts to read the information on the actual chips indicates that the writing on them is the same. Please check yours as I have always considered these generic.
I had guessed that the three coil fail errors on the EGR would be connected to the three ecu chips but it certainly appears that the buck stops at the single chip. Certainly, the resistors and connections are there. Not immediately obvious where the connectors on the pair of other chips go.
The problem with removal/refit of these chips is not so much the chip but sorting out vapourised pads and tracks. I did one recently and the P1499 code was exorcised but now there are P1497 and P1498 codes. I did check all the connections but have to say it would appear to be related to that single chip. Perhaps replumbing the main chip has facilitated detection of unseen damage to the other 2 chips?
By all means have a go at repair yourself but I would advise you will need another good chip and a hot air station for removal/refit of the chip as well as s good soldering iron to repair / reconfigure board damage.
Okayyy… that sounds a bit above my board. Time to tap out and get someone who’s a bit more talented than me to help out. Would you have any suggestions on where I could get this fixed and how much I should expect to pay?
Here’s a couple better pictures if that helps
The new pictures are much clearer or rather, less unclear:-)
No damage to the EGR associated chips that I can see.
(Sorry not to have checked back on the thread for a week or two.) Those better photos show the designation written on the chips. A google for SDK06 and SDC09 suggests both are transistor arrays made by Sanken. The former contains 4 mosfets and the latter two bipolar transistors. I can have a look around to see if I can find a supplier or an equivalent if it might be useful. Although I’m not daunted by changing these types of small outline package chips I appreciate it’s a soldering job that many would prefer to avoid.
{edit to add] Some suppliers of SDC09 show up on eBay, but they want £12-15 per chip which seems steep. Not found anyone selling SDK06.
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Nice one Martin.
I spent ages doing a repair on one of these ecus recently and it did not work. Having tested all the connections, tracks, etc, the repair should have worked. It did get rid of the P1499 code but resulted in a P1497 and a P1498.
Now after your post I realise that I replaced the single SDK06 chip with an SDC09.
I would say more than a fair chance that this has caused the issue.
The best way I have found of removing and refitting these chips is with a hot air station rather than a soldering iron. Certainly, removal with an iron will only deal with one leg at a time and necessitate bending each leg up, so it does not reattach.
The chip that seems to blow is the front singular SDK06; not seen any of the pair of SDC09s damaged on the EGR damaged ecus encountered.
SDK09 are available here; need to buy 5 and $8.40 airmail but cheap enough.
You are probably already aware of this essential precaution, so please forgive me if I’m teaching you how to suck eggs!
Depending on the substrate of the PCB, it is possible to destroy vias linking layers simply by soldering, even hot air.
However there is an easy prevention; dehydrate the PCB in an 80C oven, no hotter, for a few hours immediately before doing the soldering. All components will be fine, especially since they’ll be unpowered.
The problem is moisture trapped inside the board substrate turning to steam and splitting its laminations apart, not by much, but just enough.
Been there, done it!! Fortunately I had some more prototypes to play with.
The only exception to this heating is any type of battery, these should be removed (snipped) before any work on a PCB.
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Hi! Sorry that haven’t replied for a little while. Thank for you for all of the insight! Although I am still feeling a little stumped. If there appears to be no damage to the chips, then why else might I be getting the P1498 code? Thanks
It’s a good question and I don’t have a 100% confident answer as not sure what, if any ecu damage a sole P1498 associated fault could cause. I am all too familiar with P1499 and the destroyed chip and burn damage that causes. Perhaps someone else has replaced their EGR stepper motor after a P1498 and can comment on whether there is reciprocal damage to the ECU?
If I had to guess, I would say the new EGR you fitted is fubarred, although if both old and replacement produced this same error code, highly unlikely?
