I'm looking for engine compartment harness diagrams for 1991 Chevy and GMC C/K truck, with the bulkhead connector and circuit number list.
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I'm looking for engine compartment harness diagrams for 1991 Chevy and GMC C/K truck, with the bulkhead connector and circuit number list.
Does this help?
BLG
When that body style truck was equipped with EFI the harness was routed through the firewall just above and to the passenger side of the distributor using a rubber grommet. If you have a harness from the older square body truck there are very few connections with the main harness.
In the next generation trucks the harness is routed under the heater box on the passenger side. There is no connector where the harness passes through the firewall. Instead, there's a plastic "pass through" interface which is filled with sealant (ugly stuff to cut or remove) and bolted to the firewall. Some years have a narrow, rectangular pass through connector and some (I believe the later years) use a larger squared part.
If you are looking for diagrams for C100, the bulkhead connector on the driver's firewall, I can obtain them. It helps to know truck model the harness came from (C/K 1500/2500/3500).
1991 two wheel drive C3500. 350 V8, 700R4. It had air conditioning but did not have cruise control.
I'm planning on upgrading the gauge cluster from the simple idiot light one it has to the one with oil, amp and temp gauges.
Ahhh... I'll try to dig it up later today. Do you have C100 / bulkhead for the 82?
This is what I have for the 1991 1500 C/K , hope it helps.
TOM
Those may help. Thanks.
Looking more and more like I should just cut the bleeping thing off at the inside of the ECM bulkhead plug and start from there. I went to a GM dealer's service department today and they dug out a 1991 C/K wiring diagram book. I got a copy of the image of the bulkhead connector with all the circuit numbers in the boxes.
Fat lot of good that does since the book does not have a nice listing of what all the circuit numbers are, like the 1980's books have on the first few pages. One must peruse the book for ages and make many notes just to track down what goes where.
Far too logical for all those wiring books to devote a few pages to connector diagrams with complete circuit number lists right by each diagram. Nooo, couldn't have that!
Compiling such data would be in the best interests of the automotive hacking community.
The books change format over the years. You train and learn to use the new format when it comes out and you're good. They changed them again, substantially in '96. Suddenly GM manuals looked a lot like Ford books. It's a mess each time they get changed. Now it's in electronic format whaich is a completely new way to find (or not find) the info.
The circuit numbers are in the wiring diagrams that are in the electrical manual. The images posted here are from the service manual. The electrical manuals have much more detail than the simple pictorial schematics including wire sizes, colors, splices, and (usually) connector pinouts. You probably noticed this looking at the dealer's book. If my memory hasn't gone completely, connector pinouts were placed in one section and listed by connector number starting at LF of vehicle. Except for ecm connectors, of course, which are in section 6E of the service manual.
I'm still waiting for my service information provider to send the image of C100. I'll probably hit them up for the circuit listing when it comes in.
This what you are all looking for ?
This may be for the later '96-98 Vortec stuff now that I look at it , I can check the files tonight if need be .
TOM
The 1991 wiring diagrams break out C100 into about 14 pages of circuits. I can get specific diagrams if needed. These are (or should be) related to the instrument cluster.
Please let me know if this helps.
Looks different. The 91 connector is pretty similar to the 82 connector, has a "claw" on one side to hold other plugs but there are more contacts in the 91's connector.
Can I connect the old oil pressure gauge in parallel with the sensor at the rear of the engine, by the distributor, or will I need a separate sensor? I'm planning on upgrading the idiot light cluster to the gauge one that has oil pressure, temp and amp gauges. The 91 engine already has separate temp sensors for the computer (front crossover on intake) and gauge (left head). Will have to change connectors on the temp wire to use the 91 sensor.
Looking at the 1980's diagram I found showing all three clusters, looks like all the wiring is in the connector, just change clusters and make sure to have the right switches or sensors for oil pressure and coolant temp.
The original configuration for '91 placed the OP switch above the oil filter on the LF side of the block and a switch (for the fuel pump) at the top of the block. Later configurations came with a combination switch/sender. Either sender works with the guages, provided the range is correct (0-40 psi or 0-80 psi.)
This has the big plastic sensor with three wires in a 90 degree fitting atop a tall pipe by the distributor. I replaced it because it was leaking oil.
Yes... but are all three wires used? There's no use for a pressure reading for anything other than the gauge. So if all three wires are used, two would be for the fuel pump circuit and I would suspect the third triggers a warning light on the dash. I don't remember that being the case but hey... it's been a *few* years since I worked on these trucks. Now if that's the case then you could replace that sender with an actual pressure sensor / switch combination and connect the gauge directly to the circuit formerly used for a warning light.
But ultimately, if you have the room it won't hurt anything to Tee the gauge sender and that unit to the same point in the block.
I got the cluster out of the 91. It has oil pressure, amp and temp gauges.