Page 10 (Updated 10 -Nov-2008)
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Groundings, ESD:
Boosting Maxima Electronics
- GND - Groundings Overview
- Ensuring Flow
- Modifications to secure functionality
- Maxima Harness Grounding Points
- ESD
- Danger!
Free Service Manual, Free Download.....see FAVORITE LINKS -page 26- FAVORITE LINKS
Proven: Eletric Motors Do Work without GROUND !
However, please Continue reading, stay tuned:
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Groundings Overview
Car manufacturing is volume production and their success depends on cost cutting. One place almost all manufacturers cut corners is wiring, and wiring thickness.
Luckily Maxima has high quality connectors! (On 10 yr. olds they have to be all cleaned)
Typically first five years (warranty period) goes well, but later...
Groundings do matter:
One of the many reasons for grounding, quote:
"Have you ever seen sparks shooting off the lower pulley of a Quad Four engine? Craziest thing I ever saw. At first, I thought it was some kind of a secondary ignition leak, but it isn't. It's simply static electricity being produced by the drive belts.... "http://www.picotech.com/auto/tutorials/ignition-primary.html
Nissan distributor grounding will fail, the only question is when. This will result in malfunctioning, intermittently sputtering engine.
When ABS groundings fail, first indication is 'jerky' braking.
System Ground:
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Electrical devices need supply voltage. The current flow through the device produces the energy for it. Thereby the flow needs a place to go. This source to drain the current is commonly called the ground.
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Ensuring Flow:
Electronic devices are suspect to interference from spikes produced by powerful devices, like starter etc. Thereby they typically are isolated from this ground, and have their own gnd 'source'.
Electrical vs. Electronics:
In electrical devices, adding extra groundings will generally never do harm, only increases reliability. In electronics one has to think also radio frequencies: a loop forms an antenna which may induce problems to the low voltage electronics devices. Thereby all electronics grounding cables networks must have to form a tree [never a loop].
Disconnection sits waiting:
A car has battery (& alternator) and its negative pole -the gnd- is strapped to chassis and engine block. Typically this is enough on new and clean products. However, oxidation between various parts, result in disconnection and/or resistance inhibiting current flow. This oxidation will arrive regardless of what u do ... except if contact grease is used: see bottom of page 14.
Adding Extra Groundings:
Extra grounding straps do ensure grounding between chassis and the engine parts. One part is the exhaust pipe, typically it has to be grounded cause the O2 sensor & other possible interference problems.
Adding your own extra grounding from chassis to alternator is imperative. Manufacturers leave this device to ground itself just via its support bolts which will oxidize, question is just how fast. Oxidation will break this ground, and ruin battery as it will never become fully charged. Add one strap between alternator body and vehicle chassis - all connection points clean & electric conducting grease added.
GND Wire thickness:
Extra gnd wire -finger thick- between engine and chassis is good to have to ensure high current flow induced by starting. Starter may consume over 500Amps and thus needs thick wire. That in case of std gnd wire failure, which is typical from 5yr olds and up. Here's no other rules except mechanical: engine moves and the wire(s) should allow free play.
Another extra thick wire is necessary between alternator shroud and engine/or/chassis (if/when alt looses contact to gnd, rectifier diodes will blow). Note that there already is one factory installed - in 3 gen maximas [NOT 5th gen!].
All other ground wires carry only minuscle currents, and their thickness is irrelevant. The 'kits' you see on the market, typically contain unnecessary thick wiring (good looks is a good sales argument:) just to discharge induced Hi Voltage BUT low Amps static charges.
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Mechanically Induced Elecricity:
There are also mechanical reasons for grounding - any revolving steel objects create currents seeking to jump onto lower energy plane. This causes sparking, thus component surface corrosion wear. Gearboxes wear down in some cases, mainly this is industrial problem and remedy is axle ground strips. Check industrial wear problematics http://www.gaussbusters.com/ppm93.html
Design is flawed in all cars:
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Anyways, I think cars (not just maxima) have poor electronics design as default and they have inherited systems designed only for climate controlled rooms within one small box. All longer distances in computing world use special drivers with CRC & other error correcting signal transmission methods, alas these are nowhere to be seen in cars. Extra long cabling for DC supply plus the digital/analog signal to noise -ratio would be laughable if I could stop crying... Dunno understand why cars even work...
Typically you lose one volt per meter on those lousy thin car wires. Doubling or quadrupling wiring thickness is always beneficial.
Ground kit is the Solution?
Electrical GND kit is important; but its only half story... and maybe even not that: ECU driven things get their ELECTRONIC-ground AND + supply via ECU thinny skinny wires. AND ECU & 'all' ECU controlled sensor wirings are isolated from Electrical chassis ground like tranny box.
Industrial applications typically speak/utilize of PE =electronics ground and XPE =electrical chassis ground. I suspect Nissan etc designers have no info (!) of these basic grounding principals: at least knock sensor and injectors seem to ground to PE, not into ECU's XPE as they should...
What is PE -or- XPE Ground?
The next picture outlines chassis ground PE and how all computers ECU, ABS, etc. are connected to there. However, all their sensors get grounding XPE only via the computer itself. The sensors should never ! be connected to PE, which sadly is not the case in all Maxima sensors...
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THEY'RE SEPARATE:
PE shields from inductive pulses in the chassis and its mechanical parts, but will not help current flow in a computer driven device circuitry which does (never!?) ground to chassis. XPE is used for the electronics signal processing, and the Nissan thinny wires provided for them is a black sinkhole... Not to mention those poor voltage (0-5V) levels [no driver circuits =cheap] used in car computers. All these grounding issues practically mean that ECU electronics is fighting always on the starving edge, and at first sign of oxidation (will come, when?) will kill u car, blink all lights with all ECU codes...
XPE ground = computer signal wires should be shielded. This shield [not seen in car applications] should be grounded only into PE. (did not add that to the pic, would have been too crowded)
Last word: If you have a chance to triple all ECU wires in thickness plus shield them, do so!
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GND-Modifications to secure functionality
Alternator Grounding
The first one you should do: alternator ground. Note: wire thickness matters in this application; the thicker the better. Alternator shroud connection: this ensures that charge voltage ground will not be cut off due to oxidation. Saves battery and the voltage regulator from frying.
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Alternator add on Ground wirings
Alternator supply wire connectors (white; this view from below) and grounding to chassis. See white oxidation cake on screw and connector; rust in the chassis hole threads.
Everything was looking so good and peaceful, until:
Alternator ground: connection via rusted threads on chassis & screw, via white oxidation cake and via rustfree painted(!) chassis. Nissan thinks this is owners responsibility: clean, add contact grease into connectors and into the grounding. (This car is 12yrs old, 80k, always kept in warm garage, no rust.) This connection was a cause of dead battery.
Btw, I've found similar ground bolt oxidation 'cakes' under a year old computer power supply, in filtered air, clean network center with A/C, all structures shiny anodized steel. Guess what the customer was saying of his equipment reliability: "...last chance before this is outta windows..." This indicates that oxidation source is in the manufacturing process, not how the equipment is stored or kept. (--->Clean & Use contact grease to block oxygen access to contacts).
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Distributor ground.
Distributor ground cleaned, add on wire installed to chassis. Crank angle sensor which is inside the distributor, needs good grounding to give adequate timing pulses. The other end of Distributor grounding wire was installed on the passenger side inner mudguard chassis wall [beside the ABS assy].
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Distributor ground wire. At right, the connector (red colored) has been modified, moved on top of the assembly, contact grease added.
The grounding pin has two possible bad contacts: the flat male grounding pin screwed to the distributor, PLUS the wire amp-connector attached to this male pin. The flat male connector is attached below, and its oxidation is hidden...
I got the attachment screw loose by hitting the outer edge of the screw end that is visible, with flat screwdriver and hammer. I managed to turn it loose from the 'wrong' side. (Some places sell also angle screwdrivers which might fit.)
If that does not succeed: mark distributor position, take distr off and get the screw out, male connector slip loose. Grind one side of the conn pin so that it fits in, clean surfaces, add contact grease, and this time put it on top. Btw. The add-on -wire works well also on any of the three distr cap attachement screws; they are connected to the distributor base.
Here the wire gauge does not matter; only static discharge grounding. (On alternator the wire should be thick; it is possible to have 50A currents flowing there.)
Testing against GND contact -failure:
All the groundings can be verified against possible problems simply attaching a test wire. Below a pic how to test the distributor groundings: if this does not help in any way, grounding work at this moment will NOT help.
The distributor cap screw is in contact with distributor. The other end of test wire is grounded on any engine ground point, here intake screw..
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ABS brake pump assembly Grounding .
ABS brake assy main ground. This original black wire is major ABS system gnd wire connector and should be cleaned, contact grease added. (see p.18)
ABS brake assy main ground.
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Maxima Grounding Points
Harness Grounding Points - for you to check and clean!
Engine bay:
Harness ground points: open, clean... Arrows CW from low left corner: ABS ground, Harness ground points (4pcs), Main battery chassis ground.
...add bit of connector grease.
Cabin:
On both front sides
...clean, add bit of connector grease, tighten.
Trunk:
On both front sides... Here is the ABS control box and its harness (1.). Grounding wire goes through the 'shelf' inside the cabin and connects on top of it.
...clean, add bit of connector grease, tighten.
Under belly, exhaust & O2 grounding.
If wire connector crimps are oxidized, DIY new wire (black arrow). Install connectors on other sides, get more direct grounding (white arrow).
...clean, add bit of connector grease, tighten.
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NISSAN main ground
(applies to wide variety of Nissans)
Main chassis ground is hidden under battery tray. Take them off, open the grounding, clean, add contact grease plus shroud the whole open wire watertight with self vulcanizing rubber tape. My car (...clean like new it was) voltage level was boosted up 0,5 volts after this operation! (Typical Nissan gnd: my 2.gen had here a real problem: one morning no start, this connection oxidized off...)
Battery negative cable - chassis connection.
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ESD Electrostatic Discharge
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Everyone playing with computers knows this menace: Dry ambient air with some fabrics create high voltage (up to 15KV =15.000V) charged electrons waiting to be grounded at any lower potential. If this arching (electrons jump, spark) happens to be electronics components, they most probably die. The electrons always search for the shortest way to lowest potential, be it thunder in nature, or ESD in 'maxima nature'...
Fuses do not protect electronics from spikes, they're way too slow for that. Fuses are for shielding electrical components. Fuse may cut off in 100mS, but Integrated Circuit = IC takes only 1nS to burn. This speed difference is about 1/1000.
IC's on Printed Circuit Boards =PCB's have diode arrays to protect them for spikes. If one or few protections fail on lesser sparks, that probably will no kill the IC's. This however degrades the shield. Do that few times and then there is nothing but direct path to the IC 'guts', gate arrays etc. Next small spike then kills the IC. With full blown 15.000V ESD spark, no diode arrays can protect the IC's.
Note: Do NOT open your battery cables while engine running. This will not cause ESD, but other spikes and voltage fluctuations potentially destroying IC's.
Unproper component handling is like roulette, u may play that quite long, only some in your the ring will suffer from holes...
Proper Electronics Handling: Wrist gnd wrap, ESD table, ESD packaging etc...
Proper Electronics Handling
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Expanding this issue to electronics overall: you have to be as careful as with any computer parts. Even with battery disconnected, you may fry one or more of the 'twenty' maxima computers. This can be done simply by having a hairy pullover on while working: fabrics create typically 4-15kV spikes, while electronics IC diode arrays can withhold only .5kV at best. These sparks contain so few microamps that humans will not be harmed.
Think about this, as u take u car in a shop: have u seen anyone using grounding wrist wraps ever, anywhere while handling electronic components? NO! And still that is the basic standard in any PC shop. --->The ultra LOW very basics... lol about stealership "maintenance" instant experts...
In any place handling electronics, the floor has to be specially ESD conducting, people must wear special conducting ESD shoes and ESD clothes for it, humidity has to be between 30-80% etc etc. How many car facilities handling electronics fulfill these basic requirements? lol.
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Note: Luckily ECU, TCU and most maxima computers are already packed in shielding steel boxes...
If these requirement are not met, all electronics have to be packaged into conducting plastic packaged specifically designed for electronics. They must be sealed, and tamper proof to shield off any instant expert...
The harness and any metal parts have capacity to eat most of these spikes, otherwise the vehicles would be absolute scrap after one service call.
...I will let no expert enter near my car.
How to handle Printed Circuit Boards PCB's
No. NO. NOOO! =UN -proper Handling. Finger touching: acids, grease to pin surfaces. ESD creating enviro: pullovers, paper, stacking, dropping
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What can you do as you surely will not buy that wrist wrap?
- Never use statically chargeable clothes
- Never touch bare IC components
- Always touch open PCB’s only from edges (see pic above)
- Never touch connector pins with finger
- Never leave PCB’s floating around
- Always touch metal surfaces while handling electronics =keep grounded. Even non grounded small metal pieces can be used for this, as the high voltages has so low amps that they will 'consume' the potential...
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!Danger! ... to be Dead -or- Grounded
Keep Grounding; What may happen if u don't behave at the gas pump?
"...Mrs. Shager drove her 1999 Ford Ranger to a self-service gas station, engaged the nozzle’s hold-open clip to have it fill automatically, then sat in her vehicle.When the tank was full, she slid out and reached for the nozzle. Touching it, she felt a shock. “Then fire kind of came out of the tank,” she said. Mrs. Shager ran into the station’s convenience store for a fire extinguisher, but flames were already leaping over her truck. By the time firefighters controlled the blaze, the pickup was a charred ruin..."
Read the whole NYTimes 07/2008 -article: Static Discharge at the pump
OBITUARIES a'la NYTimes: As usual, all stories revealing facts will be removed - if by error the censors have missed them. The NYT -story has now been censored :(
How to behave, not to succumb to the same fate as Mrs. Shager:
- Keep kids inside, all the time while filling tank
- No in/out traffic during filling: 'Driver' stays out the whole fillup time
- !Never! use static creating clothes - causing extensive static discharge sparking
- Fill the tank: never let the pistol go from your hands (it is grounded). If you have to let it go, always ground your hand placing it onto your vehicle (far away from open tank) before touching the pistol. Likewise, ground yourself before closing the cap.
- Keep car seats anti-static
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Stay alive - THINK:
Do Not let sparks to:
- Accumulate in your clothing.
- Jump free around Gas Fumes, Electronics.
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"Who hath divided a watercourse for the overflowing of waters, or a way for the lightning of thunder" ; Job
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