P1526 and p1540 codes - Mazda Forum
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post #1 of 2 (permalink) Old 09-29-2018, 06:45 PM Thread Starter
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P1526 and p1540 codes

Hey everybody! Really have enjoyed the helpful posts I've used since buying this 1999 millennia with the Miller Cycle 2.3l motor. A little background never hurts, so here's the story to date. I bought this car here in Texas from a college student. He had owned it for 9 years. Yep, still in college 9 years later! Anyways, he had owned the car for years. It has 122,000 miles. Everything works, all electrical, everything... What I did have that finally made him let it go was oil leaks EVERYWHERE! So I started researching common issues. After inspection I determined that for sure the rear valve cover gasket was leaking. Dripping pretty much right onto the exhaust and smoking like a son of a gun. So using the very informative thread that was recently reported I tore down the top end of the engine and replaced the valve cover gaskets. I replaced what vacuum hoses that needed replacement and put it all back together. Took it out for a test drive and the TCS light came on and it went into limp mode. Let me add this, the TCS light came on when I test drove it in a parking lot. I never really got on it, just wanted to make sure that it shifted well, CV joints didn't click, brakes worked etc... So the condition was preexisting. I hooked up a smoke machine and only found one tee that was really too small for the ID of the vacuum hose. But I don't think it was enough of a leak to throw the TCS. I took it to O'Reilly's and they pulled p1526 and p1540 codes. After reading on these and finding that the typical causes were either misrouting of hoses, leaks or issues with vacuum solenoids was when I tested with smoke. So the next step was to ohm out the solenoids. So it is here that I am currently at. Couple of questions/observations first.
1. Several threads indicated that there are 4 solenoids (or parts) on the tree that is bolted to the rear vlave cover. Mine has only 3. (?)

2. I ohmed the first one (closest to the passenger side) warm and it read 39 ohms.

3i ohmed the second one (the one in the middle) and got a reading of around 198 ohms. Based on what I've read, this one sounds bad and can be the cause of my limp mode issue.

Any assistance and/or advice on this would be greatly appreciated . Again, awesome community. I'm in the Ford Galaxie community as well as the RAV4 community and have always found helpful advice. This Millie is a challenge and I would definitely not advise the spark plugs and changing shade tree guy to attempt working on it. There was a couple times it felt like I would NEVER get this car back together!

Look forward to hearing from you all!
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post #2 of 2 (permalink) Old 10-01-2018, 07:02 PM
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I would definitely replace that solenoid but another thing to look for are the big hoses on the side of the throttle body one has a check valve in it and break booster hose and replace all spring clamps with real hose clamps. I have been fighting the 1540 code for awhile now and think I have narrowed it down to the break booster hose being hard and dry rotten and wont seal on the hard line for the pump. Just haven't had time to replace it yet.
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