'99 Accord Blinking Oil Light -- sanity check

Hi,
Before anyone flames me...no, I'm not taking any chances with a
blinking oil light - the car is not going to be driven until I figure
out what to do. I just want to take a shot at fixing it myself before
I get into the $70 per hour rate at the dealer. Here's the skinny:

1999 Honda Accord 4 cylinder with 116K miles. Bought used about 1K
miles ago.

I changed the oil, and put on a non-Honda oil filter (STP). Car ran
fine for about 1K miles -- now the oil light blinks intermittently. It
will blink for about a minute, then go off for 10-15 minutes, then
blink again. No matter what the driving situation. After the first
couple of times I saw this, I stopped driving the car, it's sitting in
my garage now.

I called the dealer, and the lead service guy told me that when they
see this it is always the oil sender switch. He said if it were really
a mechanical problem, the light would blink all the time.

So, I figure that for $10 (cost of switch), I'll just change it, and
I'll also switch to a Honda labeled oil filter, from the dealer.

Questions: Anyone else been through anything like this? Could the STP
oil filter have been the culprit? Does the analysis/conclusion make
sense -- that if it were really a mechanical issue, the light would
stay on all the time?

Thanks,
Randy

 

-----------------------

I saw a Honda tech bulliten that mentioned unwrapping the filters
carefully, and especially NOT to poke a pen / screwdriver thru the hole
because bits of cellophane get left inside the filter, and migrate into
the engine, causing oil starvation.

Another possibility . . .When you changed the oil, you drained out all
the STP (or whatever) the previous owner had filled the engine with to
MASK an oil problem.

Quickest answer might be to change the oil again, or at least just the
filter. It's never a bad idea on a vehicle that's new-to-you anyhow

'Curly'

 

On B-series engined cars, the oil pressure sender is right next to the oil
filter. If the proper filter socket is not used to remove the filter, the
strap/chain/bar/whatever can foul on the sender, cracking the connector.
The usual result of this is a non-functional pressure light.

I don't know where your sender is or how it works, but mine works opposite
to an old-fashioned hydraulic brake light switch, grounding the light if
pressure is too low. Break the connector, and ground can't be established.
Having said that, it's possible your switch is bad, and that would be easy
enough to check by wiggling the wire at the connector with the ignition on.
If the light flickers or goes off, the sender is damaged.

It is not likely that the STP fileter is the cuplrit. If it was, and if it
were the wrong filter for your application, the most likely visible result
would be that the oil light would take an extraordinarily long time to go
off on a cold start.

 

Thanks for the replies. I had to use an 18" channel-lock pliers to get
the old filter off, so there is a chance I nudged the oil sender. But,
the car ran fine for a week with no flashing light...so the
cause/effect is kind of hard to link on that point.

I guess my course of action is to replace the sender switch (less than
$10), and just to be sure, switch to a "genuine" Honda filter (probably
around $6)....if the light still comes on after that, then I guess I'm
off to the dealer (gosh I hope not!)

-Randy

 

The oil pressure warning indicator is controlled by either the sending
unit switch or by the driver multiplex control unit. The driver mpx/cu
can command the indicator to flash; if it thinks there is a momentary
drop in oil pressure. The same thing would happen if the sending unit
wire was shorted to ground for a short time.

What should you do?
Check the oil pressure.
Then disconnect the sending unit wire; run the engine. If the light
starts blinking again, either the wire has a short or the mpx/cu is
faulty. Sending unit failure is rare and usually results in the oil
indicator either not coming on at all or stays on solid.

 

ouch...that would be bad. I'll try the disconnect check as you
suggest. The dealer seemed to say that they see this problem (blinking
light) once in awhile, and they typically end up changing the sender.

Your comments make sense, but I'm really hoping that I'm seeing a
sender that's teetering on the edge of failure.

Since there are three modes (light off, light blinking, light steady
on), doesn't that mean that the output from the sender must be analog?
Like, variable resistance based on pressure, right?

Also, to check by disconnecting, I think I'd have to ground the lead
back to the computer, correct?

Thanks,
Randy

 

Well...I replaced the oil sender...it was cheap & easy. The only
warning I'd give to anyone who might read this is that you have to be
very careful tightening the new unit into the back of the engine block.
The block is aluminum, and the sender is small with a pretty fine
thread pitch. You have to use a large (around 22 mm ?) socket, so
likely a 1/2" drive. Very easy to over torque and ruin the thread in
the engine block. I don't know what the torque spec is on this thing,
but I tightened it just a bit more than 'spark plug' torque.

Anyway, after a day's worth of driving it seems to have solved the
problem...hope it holds up as the solution.

BTW, the service guys at the dealer said there were no issues with
using a department store oil filter.

-Randy

 

This has nothing to do but in my 91 accord alot of times after I leave from
school i have the "brake light" light on in the dash, I know nothing's wrong
with my brake lights (it's doing that since I own the car), I'm just curious
this thing always light up every now and then, why!

RAT

 

Leaky tail lights, and subsequent corrosion on the main connector.