Preventative Maintenance: Engine Grounds

[97ToyCar]

I thought I might try to contribute to this board in some small way, so I had thought from time to time, I might share a bit of wisdom from the years I have been out on the road in one make of car or another.

I will see about posting some photos and edit this at a later time.

As we all are probably aware, bad grounds can wreak havoc on a car's electrical system. Modern ECM modules depend on proper grounding for signal transfer, and most sensors, if not all, are grounded on one side of the circuit. My venerable '96 Volvo 960 is notorious for acting strangely when a ground is loose, missing, or poorly connected.

The Camry is no exception. One of the nice things about the 5-SFE is that the engine grounds are fairly easy to get to. On the driver's side of the engine is one main body ground, which is beside the air box, to get to it requires removal of the air box assembly (at least for me). I like to take a stainless wire brush to the bolt, and use sandpaper on the ring connector. The I apply dielectric grease to both the bolt threads, and to the ring connector, and then reinstall. This particular ground wire leads in two directions, one end terminates at the top of the transmission housing, and the other side leads to the driver's side engine hoist hanger, which incidentally, holds the bracket stay for the upstream O2 sensor, along with others. I repeated the procedure at both ends here as well. Now. off to the passenger side...

On the passenger side, we observe that there are 2 plug together connectors, this facilitates the removal of the upper timing cover. I like to use a quality electrical cleaner on these connectors, as they will almost always corrode internally. Mine were filthy. Locate the body ground bolt on the passenger strut tower. It may be easier to access if you loosen/remove the PS reservoir, which I did. I cleaned the bolt and ring connector here as well. I sprayed the QD cleaner into the connector ends at least twice before they came clean, then lubed them with dielectric grease. One of these connectors terminates at the left engine hoist hanger, the other curls around the timing cover, and terminates at a bolt connected to the head an inch or so down.

While I was at it, I pulled my headlight connectors, sprayed them with the QD cleaner, wiped them down, and lubed them with grease as well. I won't be having problems with the headlights for a long time. Everything cleaned up nicely.

I encourage you to do this procedure as well, and if others might know of ground points I have missed, please enlighten me. A little maintenance goes a long way, and so do our Toyotas! Cheers!

[fenixus]

there is 4 engine grounds (4 wires, 2 ground bolts) and then there is 4 wire harness grounds in engine bay (plus additional 7 or so harness grounds in cabin)... all of it can be found in Electrical Wiring Diagrams for camry gen4.0, e.g.:
LINK REMOVED /Gen4/99EWD.pdf

I never used any electrical cleaners or lube/grease on them yet, just cleaned the body metal contact point and terminal with a brush. using electrical cleaner and di-electric grease sound like a good idea

[hill8570]

Gotta watch that dielectric grease -- it's an insulator, so too much of it can cause more harm than good. I tend to prefer anti-ox conductive grease for most electrical contacts.

[fenixus]

Originally Posted by hill8570

Gotta watch that dielectric grease -- it's an insulator, so too much of it can cause more harm than good. I tend to prefer anti-ox conductive grease for most electrical contacts.

good point. what product name (and from which store) do you use as conductive grease in place of di-electric grease ?

I will be attempting to re-clean and lube all grounds soon, as i believe one of them is bad on my car. so far by looking at wiring diagrams for 00-01 camry gen4.5/00-01 solara gen1.5 it seems my problem is EC ground which is on the back of intake manifold (5S-FE). this one is the harness ground for all ECM circuits AND oxygen sensors, huh sound like all my trouble in one spot.
Last time i peeked behind the intake manifold I saw a filthy dirty oily wire ... could it be that was my EC ground ? if so then no wonders why i have electrical trouble.

I will re-post pics of car harness grounds based on 99 EWD from the link I posted initially.

[fenixus]

OK, based on '99 camry EWD i copied and pasted crucial harness grounds information for both 1MZ-FE and 5S-FE regarding engine bay diagrams.

hopes it helps all people having electrical trouble with their rides (read: you chasing ghosts you cannot really grasp).

1MZ-FE engine bay (4 grounds)


5S-FE engine bay (3 grounds)

NOTE: later gen4.5 (based on 01 EWD solara) seems to have one more ground "EP" located below "EA".

Cabin harness grounds - dash area (7 grounds)


Body harness grounds (5 grounds)


on top of harness ground locations published above there are also mentioned engine grounds (4 wires, 2 bolts) which are quite meaningless for electrical components.


Some of Physical ground locations as per above diagrams:

a) engine bay
EA (1MZ-FE & 5S-FE) Right Radiator Side Support
EB (1MZ-FE & 5S-FE) Left Radiator Side Support
EC (5S–FE) Intake Manifold / (1MZ-FE) Surge Tank RH
ED (1MZ–FE) Rear Side of the Surge Tank RH
*EP (1MZ-FE & 5S-FE) Right Radiator Side Support - *for camry gen4.5 (based on solara 00-01 wiring)

b) cabin/dash
IE Cowl Side Panel LH
IF Left Kick Panel
IG Instrument Panel Brace LH
IH Instrument Panel Brace RH
II Cowl Side Panel RH
IJ Right Kick Panel
IK Right Kick Panel

c) body
BL Under the Left Center Pillar
BM Roof Left
BN Under the Right Center Pillar
BO Right Quarter Pillar
BP Back Panel Center

[hill8570]

Originally Posted by fenixus

good point. what product name (and from which store) do you use as conductive grease in place of di-electric grease?

I'll have to check the cabinet tonight, but I'm pretty sure it's just garden-variety ox-gard (the stuff you use when joining aluminum and copper wiring). I picked it up from some mom-and-pop hardware store a couple of decades back, but I'm pretty sure any Home Depot / Lowes / Ace, etc. will carry it -- it's pretty standard stuff.

Just to cover my ass...you can overdo using this stuff, too -- since it *is* conductive. A little goes a l-o-o-o-n-g way.

[73sport]

Adding to above; folks who spray degreaser and other known caustic cleaners into the engine bay; be advised of the potential risk of setting corrsion in motion in places you don't look for problems. The hundreds of electrical connections present under your hood!

Also, I may be concerned about putting anything on lighting connectors as getting anything on those high temperature bulbs (unlikley I know) could cause them to fail, so use those products sparingly iin those areas if at all.