Question about 1989 GMC K3500
Replaced ecm but still backfiring, popping, jerking and dying. Idles fine but will not run normally.
Probably not the ecm.. look for bad plug wires, vacuum leaks, timing settings, Crank Position sensor, Spark plug wires incorrectly installed, Try this.. Open the hood at night and look for the plug wires leaking.. you are looking for sparks.. I would look for disconnected Vac. hoses, broken or cracked vac hoses, ..
Posted on May 16, 2014
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Posted on Jan 02, 2017
SOURCE: ecm fuse keeps blowing
just fixed this problem, change your fuel pump module, fuel sending unit shorts out on fuel level swing arm blue wire... unfortinately you must replace it as unit because of the design, fuel pump and tank guage fuel level sending unit are a one peice item, fuel tank has to come out to change unit, about a $ 700.00 repair too... fuel pump module runs about 350 to 700 $ depending on aftermarket or factory, try to find one with a lifetime warranty even if it is $ 50.00 more worth it..labor is about $ 250 to $ 400 depending on shop labor rate... definate problem though I ahve no doubt, common problem on GM... please rate my help, thanks...
Posted on Aug 06, 2009
If reverse is ok then you have a bad shift solenoid b.There are two solenoids on the back of the valve body that are identical,it will be the one on the pasenger side.GM calls them the 1-2 and 2-3 shift solenoid but this is deceptive because it takes a combination of them being on or off to achieve every gear.Pull the pan, disconnect solenoids and check resistance across them with a volt meter.I think you are looking for less than 20 ohms but the bad one will be off the chart.Bad transmission controllers are very rare in a GM vehicle.I bet if you have codes pulled you will find a shift solenoid code.Good luck!
Posted on Feb 21, 2011
Tips for a great answer:
The IPC detects a loss of serial data communications with the ECM. The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
The automatic transmission shift lock control solenoid
The automatic transmission shift lock control switch
With the ignition in the ON position, voltage is supplied to automatic transmission shift lock control switch. Voltage flows through the normally closed contacts of the automatic transmission shift lock control switch to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is permanently grounded. This energizes the automatic transmission shift lock control solenoid causing the transmission shift lever to be physically locked in the PARK position. When the brake pedal is pressed the contacts in the automatic transmission shift lock control switch open, de-energizing the automatic transmission shift lock control solenoid. This allows the shift lever to be move out of the PARK position.
The transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The PCM supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.
You need a Tech2 scan tool to diagnose this problem ! possible range sensor !
Sep 03, 2015 | Cars & Trucks
The automatic transmission shift lock control switch
Can you or can you not take it out of park ?
Shift Lever Does Not Move with Brake Pedal Depressed
yes or no ?
The instrument panel cluster (IPC) displays the selected gear position as determined by the engine control module (ECM). The IPC receives a serial data message from the ECM indicating the gear position. The PRND321 display blanks if:
The ECM detects a malfunction in the transmission range switch circuit.
The IPC detects a loss of serial data communications with the ECM.
You have a transmission range sensor or PCM problem , Need a professional grade scan tool to diagnose the problem , well that would be the easiest way to test .You should have all modules test for DTC'S - diagnostic trouble codes ! That would point you in the right direction ! I would suggest you google class 2 serial data communication network !
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