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1975_Opel_GT-W_concept_004_2427

Electrical System


  • Suggested articles, sometimes including step-by-step procedures, are indicated with orange colored text. You can also submit YOUR Opel TechTips, for consideration by the Editor of the OMC Blitz, to: joinomc@opelclub.com
  • Because of their twisting mechanisms, ALL Opel GT's need to be inspected for cracked headlight wire insulation, just behind the headlight bulbs. Another concern is installing a relay in the Opel GT ignition circuit, to protect the ignition switch from high amperage that will eventually burn out this part. Other OMC Blitz articles concern maintenance and upgrades to various individual circuits and components.

How to Order: Reprints of Individual OMC Blitz issues, can be ordered by mail from the OMC Treasurer (3824 Franklin Ave, La Crescenta CA 91214) for $2.00 each (cost includes postage). This offer is subject to availability.

May - June 2008

Understanding relays (Opel light circuits and relay functions explained - 4 pages)

April 2006

Opel GT Steering Column Maintenance Click here for FREE Acrobat .pdf download
Includes: Disassembly, pulling the metal hub, servicing and reinstalling the GT ignition switch, replacing the turn signal ring, and steering column reassembly. (4-pages)

Feb 2006

Opel GT Fusebox Support Gusset (Bracket), 1 page (illustrated)
Design for fusebox support on GT's, when plastic housing cracks up.

Jan 2006

Opel GT Ignition Switch diagnosis and protective relay, 2 pages (illustrated)
Click here for FREE Acrobat .pdf download

Step by Step procedure for testing Opel GT ignition switch, on and off the car. Installation procedure for Radio Shack # 4-terminal protective relay into circuit.

Feb 2005

Alternator Upgrade for 1.1 Liter Engine (1989 Chevy Cavalier 2.8 V6), 1 page (illustrated)
Article shows wire pigtail hookup and source, for upgrade to a 05 amp alternator.

Aug 2004

GT Headlight Repair, 4 pages (illustrated)
Comprehensive article includes listing of past OMC and other articles on GT headlights, electrical diagnosis of relays, and step-by-step procedure of the (necessary) re-wiring of the GT headlight circuit.

June 2004

A Quartz Clock That Works, 1 page (illustrated)
Dean E. illustrates how to install quartz movement, into a GT clock.

Feb 2004

Tech Tip Request: Resistor Wire, 2 pages
Jim T. writes to request information, as to the specifications or vehicle of origin, of a ballast resistor that will work as a replacement for the original "clear" color resistor wire in a GT ignition circuit.

Jan 2004

GT Windshield Wiper Motor Wiring, 1 page
Reply to inquiry, includes Ron D's notes on identifying function of each of the color-coded wires to the motor (White = high speed mode, Yellow = low speed mode, Green = powers the motor until the wipers return to lowest position, Blue = "Brake" function that stops wipers in the lowest position), and suggests a how to test the motor's electric function, individual circuit by circuit, when wipers don't work.

Nov 2003

GT Windshield Wiper Wiring, 1 page
Ron D. details applications by wire color, to GT wiper motor.

Sept 2003

Tracing A Battery Drain, 2 pages
Dennis G. provides stsp-by-step procedure, of locating the circuit causing a current drain with a test light. Ron D. adds that the battery should have a minimum 12.5 volt output for the test, and that a volt-ohm meter will indicate the amount of current drain within the circuit, which helps target the component.

April 2003

Ignition Switch Relay, 1 page (illustrated)
Otto B's schematic for installing Bosch 40 amp relay in starting circuit, to insulate GT ignition switch from circuit's high current.

April 2003

Fuse block Fix, 1 page (illustrated)
Ed J. describes electrolysis potential of fuse box terminal rivets, and his replacement of with 440 brass screws and nuts when reassembled.

May 2001

Everything You Need To Know About Batteries, 4 pages (illustrated)
Detailed generic article on battery types, technical aspects, FAQ's.

March 2001

GM Alternator in an Opel: Wiring, Bracket, 2 pages
Installation instructions for one-wire GM alternator output, including notes on amp gauge warning light circuit.

Feb 2001

Voltage Regulator Troubles, 1 page
Diagnoses include internal inspection of regulator, 3-wire loom, verifying alternator ground wire is intact and connected.

April 2000

Service Manual reprint: GT Fuse Box terminals/circuits, 1 page
Application table, lists which circuits are affected by which fuse.

Feb 2000

GT Turn signals rewiring, 1 page
Repair of the "double dash lights blinking" syndrome include checking and cleaning ground wire connections, and replacement with a 2-prong style flasher unit (includes small rewiring too).

Dec 1998

Starting system (Service Manual info), 5 pages (illustrations)
Reprint of text and illustrations on starter system, from 1973 Opel Service Manual. Includes disassembly and internal repair of starter.

Jul 1998

Electrical Charging System; 3 pages
Multi-part discussion of expected amp gauge settings, measurements of voltage in circuit from alternator to fusebox, need to check and repair dashboard gauge ground wire connections (including the windshield wiper motor's ground wire),

Dec 1997

Troubleshooting dash lights; 1 page
Elliot B. mentions that if dash turn signal indicators flash when the engine is starting, it could be a loose connection at the starter solenoid.

July 1997

Pertronix Electronic Ignition, 1 page (illustrated)
Introduction and photo, of the Pertronix 1847-V Ignitor, which can be installed as a replacement for the sometimes troublesome Opel ignition points in the distributor.

Jun 1997

Repairing turn signal problems, 1/4 page
Joel R. reminder to connect ground wire to 10mm bolt on steering column.

Dec 1996

Instrument panel lights; 1/2 page
Roger K. mentions light bulbs above cigarette lighter (70-73 GT). Next tip mentions source for clock light bulb is VDO (gauge mf'r).

Nov 1996

Fixing a clock; 1 page
Roger K. informs that bypassing an internal (usually shorted out) fusible link wire will fix most Opel clocks. Lube and test with 12VDC.

Jun 1996

"Looney Tune & Merry Melodies" & "Installing a Stereo in your GT"; 4 pages
Details installing stereo systems in Opels. Includes section on components, and revised service manual instructions on pulling the dash gauge panel (where the unit is typically mounted). Illustrated.

Dec 1995

"Opel Blinker System Revealed," 1 page (illustrated)
Explains operation and troubleshooting the GT flasher system. Suggests checking for burnt-out bulbs and good ground connections.

July 1995

Reply to Letter (Non-Functioning Ammeter), 1 page
Notes that a common wire bypass (from the "B+" terminal of the alternator) will cause the ammeter to not function. The circuit is routed through the ammeter, otherwise it will not display a charge.

Sept 1994

GT Ignition Switch Lubrication Tech Tip; 1 page
Suggests spraying WD40 in "cross shaped" center of the switch (when the steering column has been disassembled) to prevent premature ignition switch failure due to burn-up of internal carbon deposits.

Nov 1993

GT Turn Signal Flasher Relay Part; 1 page
Ron I. describes Lucas #SFB164 as a replacement for the GT flasher relay.

Dec 1991

GT Ignition Contact Switch Protective Relay Tip; 1 page (illustration)
Gil W. describes how to add Radio Shack #275-226 relay to starting circuit in engine compartment, to prevent failure of GT ignition switch. Upgraded ignition circuit schematic is illustrated.

March 1990

Ignition System Tips, Putting a Better Spark in Your Opel; 2 pages
Roger L. suggests an upgraded ignition system including: Pertronix Magnetic Ignitor #1847-V kit, stock Opel distributor modified for full recurved centrifugal (no vacuum) advance, Jacobs #400704 spark plug wires, Jacobs #380672 ignition coil, and Jacobs #370406 computer unit (to 6500 rpm's) and Autolite 273 spark plugs. (Note: replacing the points with Pertronix unit can lead to a sudden breakdown, also DON'T Jump the Battery with a Pertronix installed -- pull the wires from the ignition coil first, to avoid "blowing" the Pertronix module unit!).

Feb 1990

Alternator: Installing GM Series 10 SI on Opel (Letter); 2 pages (illustration)
Joseph S. writes that the typical 1969-1990 GM (non-Opel) alternator produced a 35-63 amp output, and will mount in an Opel with alterations such as common 5/16" flat washers and drilling a piece of 3/8" diameter tube with a 5/16" bit to fit. The upper mount bracket also has to be cut and welded to a bracket tip from a 1960's Chevy for the correct angle (illustrated), and a larger (est 36") fan belt must be used. The wiring circuit needs adaptation, as the GM alternator has an internal voltage regulator.

Feb 1989

Opel GT Fuse Box Repair; 2 pages (illustrations)
William S. describes and illustrates a replacement GT fusebox housing and installation procedure.

June 1988

GT Fuse Box Reinforcement "Gusset"; 1 page (illustration)
Gil W. designed and illustrates a custom metal plate, which can be mounted on the front studs of the GT fusebox, to support the frequently - cracked and broken plastic front fusebox mounting surface.

Sept 1986

Distributor Ignition Point System Tech Tips (Mallory & Allison); 1 page
Roger L. suggests that if the ignition points keep pitting (in an otherwise functioning distributor) to install a capacitive discharge ignition such as the Mallory "Hy-Fire" unit (part #29026), which isolates voltage from the points). Criag Z adds that he has installed an Allison photo-electric unit which functioned well (but that could be suject to fail at an inconvenient time or place).

Dec 1985

Standard Ignition vs. Solid State Ignition Opinions; 1 page

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