below is listed a ton of data and trouble shooting techniques:

scroll and print what you want!! or call 858-514-8388  tech line.

BACKGROUND & OPERATION

In 1962 the Delco-Remy Division of General Motors began the task of designing an ignition system that overcame the limitations of the conventional breaker-point system. The overall objective of the new Delcotronic Transistor-Controlled Magnetic Pulse-Type Ignition System (the official name) was to provide long life, high reliability, and require no periodic maintenance during the life of the vehicle.

A brief review of the limitations of the conventional breaker-point system are:

1. The available voltage to fire a spark plug cannot be increased due to the limited current carrying capabilities of the points.
2. Periodic ignition system service is required due to rubbing block wear and point erosion.
3. Distributor point bounce places a practical limit on the engine speed of which satisfactory ignition performance can be maintained.

Delco-Remy was successful in designing and manufacturing an ignition system that was superior to the conventional system and it continued to be superior for almost two decades. To quote a Society of Automotive Engineers paper dated 1963 (after the system was developed):"The new Delcotronic Transistor Controlled magnetic pulse-type ignition system provides long maintenance-free life and high reliability which have been sought for many years. It accomplishes this end by totally eliminating the components which traditionally have been most subject to inaccuracy, wear, and deterioration."

The accomplishment of Delco-Remy's goals were made possible largely by the elimination of the familiar contact point set and substituting a magnetic triggering device. This solid-state device composed of a stationary magnetic pickup assembly and a rotating pole piece, provided an excellent signal to trigger the Transistorized Ignition (TI) system.

In order to fire each spark plug, it is necessary to induce a high voltage in the ignition coil secondary winding by opening the circuit to the coil primary winding. In conventional systems, this is accomplished by opening the distributor contact points. In the TI system, this is accomplished by inducing a voltage pulse in the distributor pickup coil which is conducted to the pulse amplifier where it signals a "triggering" transistor to turn off a "switching" transistor. This action interrupts ignition primary current flow, inducing high voltage in the secondary ignition circuit. The pulse amplifier does this opening of the circuit in a more efficient manner, which in part explains the improved performance of the TI system. In addition, while contact point deterioration problems limit primary current in the conventional system to about 4.5 amps, the TI system can operate as high as 8 amps which further enhances the performance of the system.

The Deltronic ignition system (now more commonly referred to as Transistorized Ignition or TI) overcomes all of the previously mentioned limitations of the conventional system because TI:

1. Will yield higher spark plug voltage.
2. Will operate at extremely high speeds without losing ignition performance.
3. Is essentially maintenance free.

An example of the TI system superiority can be seen when looking at the output voltage at the spark plug versus the speed of the vehicle. At 10 mph a conventional system is developing 24,000 volts versus 25,000 for the TI. However, at 100 mph the conventional system is down to 17,000 volts and the TI is at 24,000, which is 40% more voltage to fire the fuel/air mixture under high load conditions. In addition to this, the system will still function properly at speeds exceeding 9,000 rpm.

COMPONENTS

The three major components that make up a TI system are a magnetic pulse distributor, an ignition pulse amplifier, and a special ignition coil. Two resistance wires are also used in the circuit; one as ballast between the coil negative terminal and ground, while the other resistance wire provides a voltage drop for the "engine run" circuit and is bypassed at cranking. The other components of the ignition system -- the spark plugs, plug wires, distributor cap and rotor -- are the same components used in a conventional system.

TROUBLESHOOTING

Most of the problems associated with the TI system can be traced to the pulse amplifier. When this system was developed, Germanium transistors were "state-of-the-art" in electronic technology. This type of transistor had many limitations (especially by today's standards) and many amplifier failures can be traced to these transistors.

Other problems that lead to amplifier failure are water from a faulty cover seal, and high voltage spikes. Moisture trapped inside the amplifier will cause corrosion to the extent it will rust electrical component leads and destroy copper tracks on the printed circuit board, thus leading to failure. High voltage spikes induced by a malfunctioning alternator or voltage regulator will fail the circuit protection device mounted on the circuit board. However, the amplifier is constructed so it can be serviced. Faulty components can be identified and replaced since the circuit board is easily accessible through the rear cover plate.

As an alternative to repairing the original circuit board there is currently available a replacement circuit board that takes advantage of today's current "state-of-the-art" technology. This "drop-in" module uses silicon transistors and is more reliable than the original circuit board.

Aside from the pulse amplifier, there are other potential problem areas. The next, in order of occurrence, is the distributor magnetic pickup assembly. The problem here is either in the lead out wires or the wire-wound coil located inside the assembly. The lead out wires have a tendency to fail from repeated flexure and sometimes this will occur inside the insulation with no evidence on the outside. A resistance check (500 to 700 ohms) should detect this problem. If there is a problem with the wire-wound coil, usually appearing as an erratic engine miss or surge, it is due to an intermittent in the windings and is usually evident only when the engine is hot. Replacement of the magnetic pickup assembly is required in this case.

Last on the list of problem areas is the ignition coil. This can fail in two modes. The first is an intermittent or break in the windings that make up the heart of the coil. The other is a cracked tower which allows the secondary voltage to be misdirected, usually jumping to one of the primary terminals. In either case, replacement of the coil is in order.

SUMMARY

Transistorized Ignition is a very unique performance option that works well, when it works. When it doesn't, it can be very frustrating. As previously mentioned, most problems can be traced to the amplifier or to the distributor pickup coil. If your car was originally equipped with TI, it is probably in your best interest from an originality and performance standpoint to retain the TI system.

#TI-139 =*NEW===T.I. INTEGRATED CIRCUIT MODULE.....$139 ...NEW T.I. WIRING HARNESS WITH ADAPTER CLIPS $99  SPECIFY YEAR ...

"original finned delco black "amplifier  BOX  " PICTURED ABOVE WITH BACK COVER OFF—READY FOR YOU TO BOLT IN 1965-1968-EARLY $295  WITH DECAL.     complete amplifier unit #5005  with new module already installed    $295

1968L-1972  $290   CRANE’S 800-597-4132

*NEW T.I. CENTER COIL (BOBBIN) & MAGNET ASSEMBLY ( A NEEDED REPLACEMENT IF YOUR MAGNET IS CRACKED AND BAD WIRES )--- WITH TWO WIRE HARNESS- CMPLETE $209=

+USED DISTRIBUTORS: OVER 30 ORIGINAL DATED DISTRIBUTORS --- OVER 50 *NEW

+=T.I. CENTER POLE PIECE NEW IN DELCO BOX-$145 EA.NEW

T.I. (SLIP-ON) COIL SLEEVES, #231,.$ 70 

NON-TI =regular TACH DRIVE Distributors. IN STOCK-REBUILD -- $259       or  GOOD USED $195.00

^^^^^^^^^^^^^^^^^^^^

VARIATIONS IN TRANSISTORIZED
IGNITION WIRING HARNESSES

The purpose of the Transistorized Ignition (TI) Wiring Harness, quite simply, is to join the three (3) TI components (distributor, amplifier, and coil) together electrically and to provide a power feed to the circuit. The TI harness, in all applications, was a separate harness that was independent of the main engine wiring harness. All six (6) TI wiring harnesses used from 1964 thru 1971 were basically constructed the same, including resistance wires (two different values) built into the harness. Other similarities are the basic layout of the harness and the material used in their construction (including the wrapping tape).

The main differences are the total length of the harness, the manner in which power is supplied from the ignition switch, and the mating connector for the amplifier.

The TI wiring harness "functions" in the following manner. When the ignition switch is turned to the "start" position, power (+12v) is fed to the system through a wire in the harness that connects to the "R" terminal of the starter solenoid. The reason for this power source is to obtain the highest voltage available for cold starting. Once the engine is running and the ignition key is released to the "run" position, due to the construction of the wiring harness, the power source is simultaneously changed to feed from the ignition switch. Between the ignition switch and the amplifier is a length of resistance wire that drops the voltage to the amplifier to approximately 5 volts. This reduced voltage is necessary for amplifier durability. The critical factor in amplifier life is temperature. The greater the voltage and current draw, the greater the amount of heat generated. Therefore, resistance wire is used in the harness design so the system works in a voltage range tolerable for the amplifier electrical components.

The second length of resistance wire connecting the amplifier to the ignition coil and to ground, is used to limit the current draw through the coil. In 1964 and 1965 this resistance wire was located between the negative side of the coil and the ground, and in 1966 through 1971 it was between the positive side of the coil and the amplifier. This explains the difference in the voltage values (3.5 versus 6 volts) at the positive coil terminal in the GM published "Breakerless Ignition System Trouble Diagnosis Procedures" (refer to 1964-65 Diagnosis and 1966-71 Diagnosis).

Now, let's look in detail at the differences between the various TI wiring harnesses. Using the 1964 harness (GM part number 2987104) as a baseline, I will describe the changes...

The 1964 harness had a total length of 88.5-inches and picked up ignition switch power from a pink wire at the firewall. It also used only one ground wire that connected the negative side of the coil to the amplifier housing.

In 1965 (GM harness number 2988817), the only change made was the total length, which grew to 93.5-inches. This was done to accommodate two (2) amplifier locations, depending on various vehicle options.

In 1966-67 (GM harness number 6289482), the total length was the same as in 1965, however another ground wire was added because the amplifier was now (as in '66) mounted to a fiberglass panel. The extra ground wire connected the amplifier attachment bolt to the radiator core support which was metal and grounded. This extra loop to ground was continued for all subsequent years.

In 1968 there were two (2) wiring harnesses used because of a change in amplifiers in January of 1968. Early-1968 harnesses (GM number 6295077) had a total length of 107-inches and the connector for early-style amplifier (GM number 1115005). Late-1968 harnesses (GM number 6295260) were changed to a total length of 106-inches and had provisions for connecting the later amplifier (GM number 1115343). Also in late-1968 harnesses, and all subsequent harnesses, the ignition power feed came directly from the back of the ignition switch through the use of a special two-wire extension.

In 1969 through 1971, the harness (GM number 6297596) was virtually identical to the late-1968 version except that it was shortened to 101-inches.

diagnosis:

ENGINE SURGE OR ERRATIC MISS CONDITION

Last modified: June 09, 2011