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4 electrical issues on the instrument cluster

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4 electrical issues on the instrument cluster

Postby 1987 CR-X HF » Wed Oct 09, 2019 11:08 pm

Hello, and thanks for checking!! It's a 1987 CRX HF. 4 problems, not sure if they're related. Car is 100% stock.

1) Tachometer is always reading at about 2/3 (ie 67%) of the actual RPM speed. I know this because when I'm doing 40 mph in 2nd, it should be at 3k but the tach is showing 2k. Note: tire size is 14" and tach started doing this suddenly.

2) Temperature gauge is erratic. It just jumps around sometimes. Must be related to the tach issue?

3) The interior air vents (HVAC vents) are stuck on floor mode. The buttons (with the orange lights) aren't doing anything. I tested the mode motor by itself and it works. The mode motor is what changes the air vents when you push the buttons.

4) Interior fan speed works at 3 and 4, but not at 1 or 2. I think this must be the blower motor resistor.

I've removed the gauge cluster and it looked fine. Some bulbs burnt out but nothing else stood out.


I got this CRX in 2006 and I'm finally giving it some TLC. Got a new clutch, brake rotors and shoes, bearings, and more for this good old car.
1987 CR-X HF
 
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Joined: Wed Oct 09, 2019 10:32 pm

Re: 4 electrical issues on the instrument cluster

Postby 1987 CR-X HF » Thu Oct 10, 2019 9:19 pm

Today I was able to find time to look into #3. I think I found the "HVAC relay" as one vendor calls it. It was located in the front / passenger side of the engine compartment, rear of the battery. I think it's a working relay but I need to do more testing.

Does anyone know if this sounds like the hvac relay? It has a black rubber cover and is bolted into the side of the engine compartment.

Not sure where I'll look if the HVAC relay works. I found a ground under the steering wheel and it was very clean.

Thanks for any help!
1987 CR-X HF
 
Posts: 7
Joined: Wed Oct 09, 2019 10:32 pm

Re: 4 electrical issues on the instrument cluster

Postby 1987 CR-X HF » Wed Oct 16, 2019 6:58 pm

Further testing of the HVAC relay proved it was working.

As for the temperature gauge, I found that the connector wire was simply disconnected. It works now!

For the heater / air vents issue, I opened the assembly (the one with the buttons) until the large chip was exposed. I found a badly burned terminal on the chip labeled HA17902P. I think this is the problem. When I was messing with it, the motor would activate. I ordered a replacement and will solder it in next week.

I ordered an ignition control module (ICM, also known as igniter) in hopes that it will fix the tach which runs really slow. The ICM usually causes a bouncing tach, but read that it can cause other weird problems. I also read a slow tach could be due to a bad alternator, but mine puts out about 14 V at idle (normal).

The blower motor now works at all speeds after installing the new blower motor resistor!
1987 CR-X HF
 
Posts: 7
Joined: Wed Oct 09, 2019 10:32 pm

Re: 4 electrical issues on the instrument cluster

Postby mudder101 » Sat Feb 15, 2020 12:26 pm

I have a cluster if you are looking

7853834011
mudder101
 
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