The idle is surging and a green flashing key on the dash

JODI NIELSEN

MEMBER
2003 HONDA CRV
2.4L
4 CYL
180,000 MILES

Details would take more pages than War and Peace. Here's my diary:

The car listed above is a California car.
Key Ignition Lock Assy finally refused to turn to Start car.
Replaced entire Key Lock Ignition Switch Assembly Unit.
Keys programmed locksmith.
Car starts. Yaya!

But previous to this the starter was beginning to fail ie whining, grind, yes that noise. As I had 2 weeks to pack up a house and vacate the starter would have ti wait. And she did. 4 months ti be exact. Had her flatbed towed and parked. Fast forward:

Replaced broken disintegrated ground bolt starter with new (Amazon) using 'from top method ie remove intake manifold evaluated to access starter bolts.
Reinstalled, reconnected, inspected and held breath. She starts! Yipee! I'm a female btw so this was a big deal for me, especially with the 'really mechanics hanging about. However, mil on.
About 3 orv4 min into the warmup, the idle drop to near conk out then suddenly rockets to 3,200RPMs! Back down, up, down, up, you know what I mean. Wtf? So I plug in trusty obdll reader and it says imrc failed. And diagnostic research suggests cleaning runners and inspecting yada yada.
So, I did. It was clean, no cracks, whatever. Reinstalled
Started. Let warm up. Down. Up. Down.

Are you still with me?
Code reader now says imrc sensor failed.
Changed. No change. Reader says iac sensor bad. Changed. No change. Reader says IAC motor bad. Changed entire throttle body with different MAP, CTS, IAC motor, and air filter.
There's a change now.
Oh, the idle is surging, we now have a green flashing key on my dash, the obdll can't communicate with the vehicle, and I have no spark at plug-to-valve cover test.
have fuel. Battery fully charged. Inspected wires where work was done. I'm ready for them. Tnt procedure. Anyone?

3 Replies

AL514

MECHANIC
4,118 POSTS

Hello, the green key flashing is the security system. The immobilizer is keeping the vehicle from starting. It will probably need to be reprogrammed. With this many problems it sounds like you may have a bulk connector in the wiring harness that may be corroded. I don't think you would have that many components fail at once. The immobilizer is linked with a lot of vehicle systems. You should probably start checking all the main bulk connectors as well as the ECM connector. The ECM on these is down under the passenger side of the dash. When you get communications back, you may still get the Intake manifold runner codes. Unfortunately, because the intake on these is plastic and so is the IMRC, it tends to warp the intake manifold. The intake is usually replaced with the valve assembly.
But as for the security system, it may be losing its keep alive memory, on the diagram below you'll notice the Immobilizer, Keyless Receiver, Multiplex Control, are all on the same constant power feed.
From the battery to the under-hood fuse box, to the under-dash fuse box. It's all linked together. You may be losing power on the feed causing the security system to lose its memory or not get powered up. The multiplex control unit on these go bad too, causing issues with the keyless entry.
But checking that this circuit is staying powered up would be a first check, you'll also notice that power for the Data Link Connector (DLC) is on this feed as well, that would explain the no communication issue too. Pin #16 of the DLC should have 12volts. Pin #4 is the Chassis Ground and Pin#5 is ECM and sensor Ground.
So, if you can track the power feed from the battery along this circuit, you may find a corroded connection or some other issue along the way. The third diagram is the data link connector pins.
The Ground G101 has a Technical Service Bulletin on it to for causing all kinds of electrical issues after repairs.

https://www.2carpros.com/articles/how-to-reset-a-security-system

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