Frequently Asked Questions

With the exception of Chrysler wiring harnesses, virtually all of our wiring harnesses, battery cables and switches may be ordered directly from us.

We do not sell any of our Chrysler, Dodge and Plymouth wiring harnesses direct; they must be ordered from our exclusive distributor Year One Inc.

Chrysler wiring harnesss descriptions, online product listings and printed catalogs are provided for informational/reference purposes only.

We offer free technical support for all of our Chrysler wiring harnesses. You are welcome to contact us directly if you have any technical questions, regardless of whether you have already purchased one of our products or are considering doing so in the future.

It's worth noting here that Chrysler Coils may be purchased directly from us or through Year One Inc.

All original "point" type distributors require no more than 9.6 volts (approximately) to operate correctly. Most GM cars use a "white cloth covered resistance wire" or an "external ballast resistor" to reduce the line voltage to the coil from 13.7 volts (approximately, when vehicle is running) to the necessary 9.6 volts (approximately). The "white cloth covered resistance wire" or a lead from an "external ballast resistor" must not be used to power a GM H.E.I. distributor. This is a common mistake that will degrade performance of the ignition system. All GM H.E.I. distributors require full system voltage of 13.7 volts (approximately, when vehicle is running) to operate at peak efficiency.

M&H has an easy solution click here.

In general, all pre 1972 factory tachs will work; however most will not read accurately. RC Tach Shop can replace the circuit board in your tach with a newer style board that will make it work and read correctly. You can reach them at (812) 989-4727.

It's worth noting that there are aftermarket "tach filters" that can be hooked in series between your distributor and tachometer that may allow your factory tach to work correctly with an electronic distributor. We have not tested and researched all the different tach and tach filter combinations, so we suggest researching the possibility in the online car forum(s) for your specific vehicle to see if it is a viable option for you.

External Voltage Regulators can be difficult to find, and are not very reliable. We suggest using a Genuine Delco internal regulated alternator for all applications.

The problem when converting from external to internal though is adapting your original harness. Not only do you need to make sure the alternator will still charge the battery, but you'll want to make sure your gauge or warning light is still able to alert you when the system is not charging.

M&H has come up with an easy and inexpensive solution click here.

The two most popular models to convert from warning lights to factory style gauges are 1967 to 1969 Camaros and 1970 to 1972 Chevelles and El Caminos. NOTE: Factory wiring schematics for gauge type cars are not available and were never produced by GM.

1967 to 1969 CAMAROS GAUGE CONVERSIONS

Camaros can be converted by using one of our console gauge conversion kits. The kit is somewhat difficult to install and requires some electrical knowledge, however it is an economical way to adapt your original harnesses to accommodate a factory style console gauge set.

The preferred method of converting a Camaro to Gauges is to replace the Dash Harness, Forward Lamp Harness, Engine Harness, and the Console Harness with gauge style harnesses. Although this is more expensive then our conversion kit, the installation is actually easier.

1970 to 1972 CHEVELLE & EL CAMINO GAUGE CONVERSIONS

All 1970 to 1972 Chevelles require replacement of the Dash Harness to a gauge type harness. 1970 to 1971 models will require replacement of the Forward Lamp Harness to a gauge type harness. 1972 models will require replacement of the Engine Harness to a gauge type harness.

For other models please call our tech department at (562) 926-9562.

Everything should match your original harness perfectly. Please keep in mind that all harnesses are built using the most current GM revision. From time to time you may notice slight differences from your original harnesses. These differences normally do not affect fit or function. If you have any questions please contact our technical support line at (562) 926-9562.

For Race Cars, Roadsters, Street Rods and Custom Wire kits we recommend American Autowire. Their extensive line of do-it-yourself kits are the best we've seen. They can be reached at (800) 482-WIRE.

YnZ's YesterdaysParts offers wiring harnesses for some Ford cars and trucks. Visit their website at YnZ's YesterdaysParts. You can reach them by phone at (909) 798-1498.

No, we only sell complete wiring harnesses. Connectors and Terminals are not available separately.

Please read this entire section for an answer to this question, and be sure to check our Product Instructions download page to see if an instruction sheet is available for your application.

Installation instructions, schematics and wiring diagrams are typically not included. We do suggest that you have a "Factory Assembly Manual" (if available for your model) on hand when installing your new harness. "Factory Assembly Manuals" contain generic black and white schematics, as well as line drawings of how to route the harnesses in your vehicle. The Manuals are available for sale directly from us, or through your local restoration parts supplier.

Many of our Specialized harnesses and kits do include instruction sheets and schematics. These include: 1947-1959 Chevy Truck Complete Wiring Sets, Camaro Console Gauge Conversion Harnesses, GTO Rally Gauge Adapter Harness, Alternator Conversion Harnesses, Classic Auto Fuse Dash Harnesses and related kits, Corvette T.I. Ignition Module, and the Breakerless SE Single Wire Ignition Kit and many others. You can download these types of Product Instructions here.

Just enter the M&H Part Number into the search box on the Product Instruction Page to see if an instruction sheet is available for a particular product. It's worth noting that you will find a link to the products instruction sheet on the products details page whenever one is available for the product.

Classic Car Wiring offers fully laminated color wiring schematics for many vehicles. Keep in mind that most wiring schematics tend to be a bit generic, they usually only illustrate a base vehicle and not one that is optioned with factory gauges, consoles, Big Blocks, A/C etc. That being said, since they are color they are very useful for troubleshooting and make a nice addition to your vehicles reference library.

Some of our Engine and Forward Lamp Harnesses utilize a special di-electric grease as original. The grease is smothered inside the bulkhead connector that mounts to the firewall. Do not remove this grease; it is a corrosion inhibitor. Do not allow the grease to get on your clothing, as it will stain.

The purple wire with the ring terminal goes to the S (or Solenoid) post on the starter solenoid.

The other wire with the same size ring terminal goes to the R (Res/Run) or C (coil) terminal on the starter solenoid. This other wire color can be Yellow, Pink, Green, Black with Pink Stripe or Black with Yellow Stripe.

The wire with the large ring terminal goes to the large B (battery) post on the starter solenoid. This connection may contain 1 or more wires, usually a heavy 10 or 12 gauge wire or fuse link wire. These wires could be Black, Red, Red & Black or Fuse Link in any of the following colors Red, Orange, Brown or Black.

The Black wire, usually 14 or 16 gauge, and usually breaking out of the harness 6 to 10 inches before the wires listed above, goes to the starter motor mounting bolt or bell housing bolt (it's a ground).

Don't be surprised, most schematics including those found in the Factory Assembly Manuals are rarely 100% correct. They are typically for a baseline car with no options. They usually fail to reflect engineering changes made during production, as well as differences due to optional equipment such as factory gauges, consoles, automatic transmissions, Big Block engines etc. Unfortunately, GM never published schematics for all the different combinations of engines, transmissions and options.

Classic Car Wiring offers fully laminated color wiring schematics for many vehicles. Once again, you must keep in mind that most wiring schematics tend to be a bit generic, they usually only illustrate a base vehicle and not one that is optioned with factory gauges, consoles, Big Blocks, A/C etc. That being said, since they are color they are very useful for troubleshooting and make a nice addition to your vehicles reference library.

Is the Neutral Safety Switch installed and working properly? Are the Neutral Safety Switch wires hooked up? Most Dash Harnesses come with Neutral Safety Switch wires installed in them. The Neutral Safety Switch wires must be hooked to a Neutral Safety Switch (in the case of an automatic transmission) or need to be joined together (in the case of a manual transmission) to complete the circuit between the starter/solenoid and ignition switch.

1958-1978 vehicles used Buss Style Fuse Boxes which use Glass type fuses. We include these Buss Style Fuse Boxes with all of our 1958-1978 Dash Harnesses unless indicated otherwise in our catalog.

1979 and Up vehicles used ATO Style Fuse Boxes which use ATO type fuses. We include these ATO Style Fuse Boxes with all of our 1979 and Up Dash Harnesses unless indicated otherwise in our catalog.

Our Classic Auto Fuse Series Dash Harnesses use ATO Style Fuse Boxes which use ATO type fuses. We include these ATO Style Fuse Boxes with all of our Classic Auto Fuse Series Dash Harnesses.

No, but most of the popular applications for these years are being manufactured by YnZ's Yesterdays Parts. You can reach them at (909) 798-1498.